@article{BoldrighiniFrigioMaponietal.2020,
author = {Boldrighini, Carlo and Frigio, Sandro and Maponi, Pierluigi and Pellegrinotti, Alessandro and Sinai, Yakov G.},
title = {3-D incompressible Navier-Stokes equations: Complex blow-up and related real flows},
series = {Lectures in pure and applied mathematics},
journal = {Lectures in pure and applied mathematics},
number = {6},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
isbn = {978-3-86956-485-2},
issn = {2199-4951},
doi = {10.25932/publishup-47220},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472201},
pages = {185 -- 194},
year = {2020},
language = {en}
}
@article{MariucciRaySzabo2020,
author = {Mariucci, Ester and Ray, Kolyan and Szabo, Botond},
title = {A Bayesian nonparametric approach to log-concave density estimation},
series = {Bernoulli : official journal of the Bernoulli Society for Mathematical Statistics and Probability},
volume = {26},
journal = {Bernoulli : official journal of the Bernoulli Society for Mathematical Statistics and Probability},
number = {2},
publisher = {International Statistical Institute},
address = {The Hague},
issn = {1350-7265},
doi = {10.3150/19-BEJ1139},
pages = {1070 -- 1097},
year = {2020},
abstract = {The estimation of a log-concave density on R is a canonical problem in the area of shape-constrained nonparametric inference. We present a Bayesian nonparametric approach to this problem based on an exponentiated Dirichlet process mixture prior and show that the posterior distribution converges to the log-concave truth at the (near-) minimax rate in Hellinger distance. Our proof proceeds by establishing a general contraction result based on the log-concave maximum likelihood estimator that prevents the need for further metric entropy calculations. We further present computationally more feasible approximations and both an empirical and hierarchical Bayes approach. All priors are illustrated numerically via simulations.},
language = {en}
}
@unpublished{AizenbergTarkhanov1999,
author = {Aizenberg, Lev A. and Tarkhanov, Nikolai Nikolaevich},
title = {A Bohr phenomenon for elliptic equations},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25547},
year = {1999},
abstract = {In 1914 Bohr proved that there is an r ∈ (0, 1) such that if a power series converges in the unit disk and its sum has modulus less than 1 then, for |z| < r, the sum of absolute values of its terms is again less than 1. Recently analogous results were obtained for functions of several variables. The aim of this paper is to comprehend the theorem of Bohr in the context of solutions to second order elliptic equations meeting the maximum principle.},
language = {en}
}
@unpublished{Witt2002,
author = {Witt, Ingo},
title = {A calculus for a class of finitely degenerate pseudodifferential operators},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26246},
year = {2002},
abstract = {For a class of degenerate pseudodifferential operators, local parametrices are constructed. This is done in the framework of a pseudodifferential calculus upon adding conditions of trace and potential type, respectively, along the boundary on which the operators degenerate.},
language = {en}
}
@unpublished{RabinovichSchulzeTarkhanov1997,
author = {Rabinovich, Vladimir and Schulze, Bert-Wolfgang and Tarkhanov, Nikolai Nikolaevich},
title = {A calculus of boundary value problems in domains with Non-Lipschitz Singular Points},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-24957},
year = {1997},
abstract = {The paper is devoted to pseudodifferential boundary value problems in domains with singular points on the boundary. The tangent cone at a singular point is allowed to degenerate. In particular, the boundary may rotate and oscillate in a neighbourhood of such a point. We show a criterion for the Fredholm property of a boundary value problem and derive estimates of solutions close to singular points.},
language = {en}
}
@article{Ly2020,
author = {Ly, Ibrahim},
title = {A Cauchy problem for the Cauchy-Riemann operator},
series = {Afrika Matematika},
volume = {32},
journal = {Afrika Matematika},
number = {1-2},
publisher = {Springer},
address = {Heidelberg},
issn = {1012-9405},
doi = {10.1007/s13370-020-00810-4},
pages = {69 -- 76},
year = {2020},
abstract = {We study the Cauchy problem for a nonlinear elliptic equation with data on a piece S of the boundary surface partial derivative X. By the Cauchy problem is meant any boundary value problem for an unknown function u in a domain X with the property that the data on S, if combined with the differential equations in X, allows one to determine all derivatives of u on S by means of functional equations. In the case of real analytic data of the Cauchy problem, the existence of a local solution near S is guaranteed by the Cauchy-Kovalevskaya theorem. We discuss a variational setting of the Cauchy problem which always possesses a generalized solution.},
language = {en}
}
@unpublished{FedchenkoTarkhanov2013,
author = {Fedchenko, Dmitry and Tarkhanov, Nikolai Nikolaevich},
title = {A Class of Toeplitz Operators in Several Variables},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68932},
year = {2013},
abstract = {We introduce the concept of Toeplitz operator associated with the Laplace-Beltrami operator on a compact Riemannian manifold with boundary. We characterise those Toeplitz operators which are Fredholm, thus initiating the index theory.},
language = {en}
}
@article{HerzogEhlertFritz2017,
author = {Herzog, Moritz and Ehlert, Antje and Fritz, Annemarie},
title = {A Competency Model of Place Value Understanding in South African Primary School Pupils},
series = {African Journal of Research in Mathematics, Science and Technology Education},
volume = {21},
journal = {African Journal of Research in Mathematics, Science and Technology Education},
publisher = {Routledge, Taylor \& Francis Group},
address = {Abingdon},
issn = {1811-7295},
doi = {10.1080/18117295.2017.1279453},
pages = {37 -- 48},
year = {2017},
abstract = {Although the general development of mathematical abilities in primary school has been the focus of many researchers, the development of place value understanding has rarely been investigated to date. This is possibly due to the lack of conceptual approaches and empirical studies related to this topic. To fill this gap, a theory-driven and empirically validated model was developed that describes five sequential conceptual levels of place value understanding. The level sequence model gives us the ability to estimate general abilities and difficulties in primary school pupils in the development of a conceptual place value understanding. The level sequence model was tried and tested in Germany, and given that number words are very differently constructed in German and in the languages used in South African classrooms, this study aims to investigate whether this level sequence model can be transferred to South Africa. The findings based on the responses of 198 Grade 2-4 learners show that the English translation of the test items results in the same item level allocation as the original German test items, especially for the three basic levels. Educational implications are provided, in particular concrete suggestions on how place value might be taught according to the model and how to collect specific empirical data related to place value understanding.},
language = {en}
}
@article{StaufferMengeshaSeifertetal.2022,
author = {Stauffer, Maxime and Mengesha, Isaak and Seifert, Konrad and Krawczuk, Igor and Fischer, Jens and Serugendo, Giovanna Di Marzo},
title = {A computational turn in policy process studies},
series = {Complexity},
volume = {2022},
journal = {Complexity},
publisher = {Wiley-Hindawi},
address = {London},
issn = {1076-2787},
doi = {10.1155/2022/8210732},
pages = {17},
year = {2022},
abstract = {The past three decades of policy process studies have seen the emergence of a clear intellectual lineage with regard to complexity. Implicitly or explicitly, scholars have employed complexity theory to examine the intricate dynamics of collective action in political contexts. However, the methodological counterparts to complexity theory, such as computational methods, are rarely used and, even if they are, they are often detached from established policy process theory. Building on a critical review of the application of complexity theory to policy process studies, we present and implement a baseline model of policy processes using the logic of coevolving networks. Our model suggests that an actor's influence depends on their environment and on exogenous events facilitating dialogue and consensus-building. Our results validate previous opinion dynamics models and generate novel patterns. Our discussion provides ground for further research and outlines the path for the field to achieve a computational turn.},
language = {en}
}
@unpublished{CattiauxDaiPraPoelly2007,
author = {Cattiaux, Patrick and Dai Pra, Paolo and Poelly, Sylvie},
title = {A constructive approach to a class of ergodic HJB equations with nonsmooth cost},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-49430},
year = {2007},
abstract = {We consider a class of ergodic Hamilton-Jacobi-Bellman (HJB) equations, related to large time asymptotics of non-smooth multiplicative functional of difusion processes. Under suitable ergodicity assumptions on the underlying difusion, we show existence of these asymptotics, and that they solve the related HJB equation in the viscosity sense.},
language = {en}
}
@article{CvetkovićConradLie2021,
author = {Cvetković, Nada and Conrad, Tim and Lie, Han Cheng},
title = {A convergent discretization method for transition path theory for diffusion processes},
series = {Multiscale modeling \& simulation : a SIAM interdisciplinary journal},
volume = {19},
journal = {Multiscale modeling \& simulation : a SIAM interdisciplinary journal},
number = {1},
publisher = {Society for Industrial and Applied Mathematics},
address = {Philadelphia},
issn = {1540-3459},
doi = {10.1137/20M1329354},
pages = {242 -- 266},
year = {2021},
abstract = {Transition path theory (TPT) for diffusion processes is a framework for analyzing the transitions of multiscale ergodic diffusion processes between disjoint metastable subsets of state space. Most methods for applying TPT involve the construction of a Markov state model on a discretization of state space that approximates the underlying diffusion process. However, the assumption of Markovianity is difficult to verify in practice, and there are to date no known error bounds or convergence results for these methods. We propose a Monte Carlo method for approximating the forward committor, probability current, and streamlines from TPT for diffusion processes. Our method uses only sample trajectory data and partitions of state space based on Voronoi tessellations. It does not require the construction of a Markovian approximating process. We rigorously prove error bounds for the approximate TPT objects and use these bounds to show convergence to their exact counterparts in the limit of arbitrarily fine discretization. We illustrate some features of our method by application to a process that solves the Smoluchowski equation on a triple-well potential.},
language = {en}
}
@unpublished{GauthierTarkhanov2004,
author = {Gauthier, Paul M. and Tarkhanov, Nikolai Nikolaevich},
title = {A covering property of the Riemann zeta-function},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26683},
year = {2004},
abstract = {For each compact subset K of the complex plane C which does not surround zero, the Riemann surface Sζ of the Riemann zeta function restricted to the critical half-strip 0 < Rs < 1/2 contains infinitely many schlicht copies of K lying 'over' K. If Sζ also contains at least one such copy, for some K which surrounds zero, then the Riemann hypothesis fails.},
language = {en}
}
@unpublished{Korey2001,
author = {Korey, Michael Brian},
title = {A decomposition of functions with vanishing mean oscillation},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25929},
year = {2001},
abstract = {A function has vanishing mean oscillation (VMO) on R up(n) if its mean oscillation - the local average of its pointwise deviation from its mean value - both is uniformly bounded over all cubes within R up(n) and converges to zero with the volume of the cube. The more restrictive class of functions with vanishing lower oscillation (VLO) arises when the mean value is replaced by the minimum value in this definition. It is shown here that each VMO function is the difference of two functions in VLO.},
language = {en}
}
@article{AlSaedyTarchanov2020,
author = {Al-Saedy, Ammar Jaffar Muhesin and Tarchanov, Nikolaj Nikolaevič},
title = {A degree theory for Lagrangian boundary value problems},
series = {Žurnal Sibirskogo Federalʹnogo Universiteta = Journal of Siberian Federal University; mathematics \& physics},
volume = {13},
journal = {Žurnal Sibirskogo Federalʹnogo Universiteta = Journal of Siberian Federal University; mathematics \& physics},
number = {1},
publisher = {Sibirskij Federalʹnyj Universitet},
address = {Krasnojarsk},
issn = {1997-1397},
doi = {10.17516/1997-1397-2020-13-1-5-25},
pages = {5 -- 25},
year = {2020},
abstract = {We study those nonlinear partial differential equations which appear as Euler-Lagrange equations of variational problems. On defining weak boundary values of solutions to such equations we initiate the theory of Lagrangian boundary value problems in spaces of appropriate smoothness. We also analyse if the concept of mapping degree of current importance applies to Lagrangian problems.},
language = {en}
}
@article{AndjelkovicSimevskiChenetal.2022,
author = {Andjelkovic, Marko and Simevski, Aleksandar and Chen, Junchao and Schrape, Oliver and Stamenkovic, Zoran and Krstić, Miloš and Ilic, Stefan and Ristic, Goran and Jaksic, Aleksandar and Vasovic, Nikola and Duane, Russell and Palma, Alberto J. and Lallena, Antonio M. and Carvajal, Miguel A.},
title = {A design concept for radiation hardened RADFET readout system for space applications},
series = {Microprocessors and microsystems},
volume = {90},
journal = {Microprocessors and microsystems},
publisher = {Elsevier},
address = {Amsterdam},
issn = {0141-9331},
doi = {10.1016/j.micpro.2022.104486},
pages = {18},
year = {2022},
abstract = {Instruments for measuring the absorbed dose and dose rate under radiation exposure, known as radiation dosimeters, are indispensable in space missions. They are composed of radiation sensors that generate current or voltage response when exposed to ionizing radiation, and processing electronics for computing the absorbed dose and dose rate. Among a wide range of existing radiation sensors, the Radiation Sensitive Field Effect Transistors (RADFETs) have unique advantages for absorbed dose measurement, and a proven record of successful exploitation in space missions. It has been shown that the RADFETs may be also used for the dose rate monitoring. In that regard, we propose a unique design concept that supports the simultaneous operation of a single RADFET as absorbed dose and dose rate monitor. This enables to reduce the cost of implementation, since the need for other types of radiation sensors can be minimized or eliminated. For processing the RADFET's response we propose a readout system composed of analog signal conditioner (ASC) and a self-adaptive multiprocessing system-on-chip (MPSoC). The soft error rate of MPSoC is monitored in real time with embedded sensors, allowing the autonomous switching between three operating modes (high-performance, de-stress and fault-tolerant), according to the application requirements and radiation conditions.},
language = {en}
}
@unpublished{Tarkhanov2003,
author = {Tarkhanov, Nikolai Nikolaevich},
title = {A fixed point formula in one complex variable},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26495},
year = {2003},
abstract = {We show a Lefschetz fixed point formula for holomorphic functions in a bounded domain D with smooth boundary in the complex plane. To introduce the Lefschetz number for a holomorphic map of D, we make use of the Bergman kernal of this domain. The Lefschetz number is proved to be the sum of usual contributions of fixed points of the map in D and contributions of boundary fixed points, these latter being different for attracting and repulsing fixed points.},
language = {en}
}
@unpublished{FedosovSchulzeTarkhanov1999,
author = {Fedosov, Boris and Schulze, Bert-Wolfgang and Tarkhanov, Nikolai Nikolaevich},
title = {A general index formula on tropic manifolds with conical points},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25501},
year = {1999},
abstract = {We solve the index problem for general elliptic pseudodifferential operators on toric manifolds with conical points.},
language = {en}
}
@unpublished{AlsaedyTarkhanov2016,
author = {Alsaedy, Ammar and Tarkhanov, Nikolai Nikolaevich},
title = {A Hilbert boundary value problem for generalised Cauchy-Riemann equations},
volume = {5},
number = {1},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-86109},
pages = {21},
year = {2016},
abstract = {We elaborate a boundary Fourier method for studying an analogue of the Hilbert problem for analytic functions within the framework of generalised Cauchy-Riemann equations. The boundary value problem need not satisfy the Shapiro-Lopatinskij condition and so it fails to be Fredholm in Sobolev spaces. We show a solvability condition of the Hilbert problem, which looks like those for ill-posed problems, and construct an explicit formula for approximate solutions.},
language = {en}
}
@article{KemptonMuenchYau2021,
author = {Kempton, Mark and M{\"u}nch, Florentin and Yau, Shing-Tung},
title = {A homology vanishing theorem for graphs with positive curvature},
series = {Communications in analysis and geometry},
volume = {29},
journal = {Communications in analysis and geometry},
number = {6},
publisher = {International Press of Boston},
address = {Somerville},
issn = {1019-8385},
doi = {10.4310/CAG.2021.v29.n6.a5},
pages = {1449 -- 1473},
year = {2021},
abstract = {We prove a homology vanishing theorem for graphs with positive Bakry-' Emery curvature, analogous to a classic result of Bochner on manifolds [3]. Specifically, we prove that if a graph has positive curvature at every vertex, then its first homology group is trivial, where the notion of homology that we use for graphs is the path homology developed by Grigor'yan, Lin, Muranov, and Yau [11]. We moreover prove that the fundamental group is finite for graphs with positive Bakry-' Emery curvature, analogous to a classic result of Myers on manifolds [22]. The proofs draw on several separate areas of graph theory, including graph coverings, gain graphs, and cycle spaces, in addition to the Bakry-Emery curvature, path homology, and graph homotopy. The main results follow as a consequence of several different relationships developed among these different areas. Specifically, we show that a graph with positive curvature cannot have a non-trivial infinite cover preserving 3-cycles and 4-cycles, and give a combinatorial interpretation of the first path homology in terms of the cycle space of a graph. Furthermore, we relate gain graphs to graph homotopy and the fundamental group developed by Grigor'yan, Lin, Muranov, and Yau [12], and obtain an alternative proof of their result that the abelianization of the fundamental group of a graph is isomorphic to the first path homology over the integers.},
language = {en}
}
@unpublished{MeleardRoelly2011,
author = {M{\´e}l{\´e}ard, Sylvie and Roelly, Sylvie},
title = {A host-parasite multilevel interacting process and continuous approximations},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-51694},
year = {2011},
abstract = {We are interested in modeling some two-level population dynamics, resulting from the interplay of ecological interactions and phenotypic variation of individuals (or hosts) and the evolution of cells (or parasites) of two types living in these individuals. The ecological parameters of the individual dynamics depend on the number of cells of each type contained by the individual and the cell dynamics depends on the trait of the invaded individual. Our models are rooted in the microscopic description of a random (discrete) population of individuals characterized by one or several adaptive traits and cells characterized by their type. The population is modeled as a stochastic point process whose generator captures the probabilistic dynamics over continuous time of birth, mutation and death for individuals and birth and death for cells. The interaction between individuals (resp. between cells) is described by a competition between individual traits (resp. between cell types). We look for tractable large population approximations. By combining various scalings on population size, birth and death rates and mutation step, the single microscopic model is shown to lead to contrasting nonlinear macroscopic limits of different nature: deterministic approximations, in the form of ordinary, integro- or partial differential equations, or probabilistic ones, like stochastic partial differential equations or superprocesses. The study of the long time behavior of these processes seems very hard and we only develop some simple cases enlightening the difficulties involved.},
language = {en}
}
@misc{Wallenta2014,
author = {Wallenta, Daniel},
title = {A Lefschetz fixed point formula for elliptic quasicomplexes},
series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
number = {885},
issn = {1866-8372},
doi = {10.25932/publishup-43547},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-435471},
pages = {577 -- 587},
year = {2014},
abstract = {In a recent paper, the Lefschetz number for endomorphisms (modulo trace class operators) of sequences of trace class curvature was introduced. We show that this is a well defined, canonical extension of the classical Lefschetz number and establish the homotopy invariance of this number. Moreover, we apply the results to show that the Lefschetz fixed point formula holds for geometric quasiendomorphisms of elliptic quasicomplexes.},
language = {en}
}
@unpublished{Wallenta2013,
author = {Wallenta, Daniel},
title = {A Lefschetz fixed point formula for elliptic quasicomplexes},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67016},
year = {2013},
abstract = {In a recent paper with N. Tarkhanov, the Lefschetz number for endomorphisms (modulo trace class operators) of sequences of trace class curvature was introduced. We show that this is a well defined, canonical extension of the classical Lefschetz number and establish the homotopy invariance of this number. Moreover, we apply the results to show that the Lefschetz fixed point formula holds for geometric quasiendomorphisms of elliptic quasicomplexes.},
language = {en}
}
@unpublished{SchulzeTarkhanov1998,
author = {Schulze, Bert-Wolfgang and Tarkhanov, Nikolai Nikolaevich},
title = {A Lefschetz fixed point formula in the relative elliptic theory},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25159},
year = {1998},
abstract = {A version of the classical Lefschetz fixed point formula is proved for the cohomology of the cone of a cochain mapping of elliptic complexes. As a particular case we show a Lefschetz formula for the relative de Rham cohomology.},
language = {en}
}
@unpublished{NazaikinskiiSchulzeSterninetal.1997,
author = {Nazaikinskii, Vladimir and Schulze, Bert-Wolfgang and Sternin, Boris and Shatalov, Victor},
title = {A Lefschetz fixed point theorem for manifolds with conical singularities},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25073},
year = {1997},
abstract = {We establish an Atiyah-Bott-Lefschetz formula for elliptic operators on manifolds with conical singular points.},
language = {en}
}
@article{MalemShinitskiOpperReichetal.2020,
author = {Malem-Shinitski, Noa and Opper, Manfred and Reich, Sebastian and Schwetlick, Lisa and Seelig, Stefan A. and Engbert, Ralf},
title = {A mathematical model of local and global attention in natural scene viewing},
series = {PLoS Computational Biology : a new community journal},
volume = {16},
journal = {PLoS Computational Biology : a new community journal},
number = {12},
publisher = {PLoS},
address = {San Fransisco},
issn = {1553-734X},
doi = {10.1371/journal.pcbi.1007880},
pages = {21},
year = {2020},
abstract = {Author summary
Switching between local and global attention is a general strategy in human information processing. We investigate whether this strategy is a viable approach to model sequences of fixations generated by a human observer in a free viewing task with natural scenes. Variants of the basic model are used to predict the experimental data based on Bayesian inference. Results indicate a high predictive power for both aggregated data and individual differences across observers. The combination of a novel model with state-of-the-art Bayesian methods lends support to our two-state model using local and global internal attention states for controlling eye movements.
Understanding the decision process underlying gaze control is an important question in cognitive neuroscience with applications in diverse fields ranging from psychology to computer vision. The decision for choosing an upcoming saccade target can be framed as a selection process between two states: Should the observer further inspect the information near the current gaze position (local attention) or continue with exploration of other patches of the given scene (global attention)? Here we propose and investigate a mathematical model motivated by switching between these two attentional states during scene viewing. The model is derived from a minimal set of assumptions that generates realistic eye movement behavior. We implemented a Bayesian approach for model parameter inference based on the model's likelihood function. In order to simplify the inference, we applied data augmentation methods that allowed the use of conjugate priors and the construction of an efficient Gibbs sampler. This approach turned out to be numerically efficient and permitted fitting interindividual differences in saccade statistics. Thus, the main contribution of our modeling approach is two-fold; first, we propose a new model for saccade generation in scene viewing. Second, we demonstrate the use of novel methods from Bayesian inference in the field of scan path modeling.},
language = {en}
}
@article{PornsawadSapsakulBoeckmann2019,
author = {Pornsawad, Pornsarp and Sapsakul, Nantawan and B{\"o}ckmann, Christine},
title = {A modified asymptotical regularization of nonlinear ill-posed problems},
series = {Mathematics},
volume = {7},
journal = {Mathematics},
edition = {5},
publisher = {MDPI},
address = {Basel, Schweiz},
issn = {2227-7390},
doi = {10.3390/math7050419},
pages = {19},
year = {2019},
abstract = {In this paper, we investigate the continuous version of modified iterative Runge-Kutta-type methods for nonlinear inverse ill-posed problems proposed in a previous work. The convergence analysis is proved under the tangential cone condition, a modified discrepancy principle, i.e., the stopping time T is a solution of ∥𝐹(𝑥𝛿(𝑇))-𝑦𝛿∥=𝜏𝛿+ for some 𝛿+>𝛿, and an appropriate source condition. We yield the optimal rate of convergence.},
language = {en}
}
@misc{PornsawadSapsakulBoeckmann2019,
author = {Pornsawad, Pornsarp and Sapsakul, Nantawan and B{\"o}ckmann, Christine},
title = {A modified asymptotical regularization of nonlinear ill-posed problems},
series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
number = {1335},
issn = {1866-8372},
doi = {10.25932/publishup-47343},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-473433},
pages = {19},
year = {2019},
abstract = {In this paper, we investigate the continuous version of modified iterative Runge-Kutta-type methods for nonlinear inverse ill-posed problems proposed in a previous work. The convergence analysis is proved under the tangential cone condition, a modified discrepancy principle, i.e., the stopping time T is a solution of ∥𝐹(𝑥𝛿(𝑇))-𝑦𝛿∥=𝜏𝛿+ for some 𝛿+>𝛿, and an appropriate source condition. We yield the optimal rate of convergence.},
language = {en}
}
@phdthesis{Zass2021,
author = {Zass, Alexander},
title = {A multifaceted study of marked Gibbs point processes},
doi = {10.25932/publishup-51277},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-512775},
school = {Universit{\"a}t Potsdam},
pages = {vii, 104},
year = {2021},
abstract = {This thesis focuses on the study of marked Gibbs point processes, in particular presenting some results on their existence and uniqueness, with ideas and techniques drawn from different areas of statistical mechanics: the entropy method from large deviations theory, cluster expansion and the Kirkwood--Salsburg equations, the Dobrushin contraction principle and disagreement percolation. We first present an existence result for infinite-volume marked Gibbs point processes. More precisely, we use the so-called entropy method (and large-deviation tools) to construct marked Gibbs point processes in R^d under quite general assumptions. In particular, the random marks belong to a general normed space S and are not bounded. Moreover, we allow for interaction functionals that may be unbounded and whose range is finite but random. The entropy method relies on showing that a family of finite-volume Gibbs point processes belongs to sequentially compact entropy level sets, and is therefore tight. We then present infinite-dimensional Langevin diffusions, that we put in interaction via a Gibbsian description. In this setting, we are able to adapt the general result above to show the existence of the associated infinite-volume measure. We also study its correlation functions via cluster expansion techniques, and obtain the uniqueness of the Gibbs process for all inverse temperatures β and activities z below a certain threshold. This method relies in first showing that the correlation functions of the process satisfy a so-called Ruelle bound, and then using it to solve a fixed point problem in an appropriate Banach space. The uniqueness domain we obtain consists then of the model parameters z and β for which such a problem has exactly one solution. Finally, we explore further the question of uniqueness of infinite-volume Gibbs point processes on R^d, in the unmarked setting. We present, in the context of repulsive interactions with a hard-core component, a novel approach to uniqueness by applying the discrete Dobrushin criterion to the continuum framework. We first fix a discretisation parameter a>0 and then study the behaviour of the uniqueness domain as a goes to 0. With this technique we are able to obtain explicit thresholds for the parameters z and β, which we then compare to existing results coming from the different methods of cluster expansion and disagreement percolation. Throughout this thesis, we illustrate our theoretical results with various examples both from classical statistical mechanics and stochastic geometry.},
language = {en}
}
@article{HedayatMahmoudiSchulze2018,
author = {Hedayat Mahmoudi, Mahdi and Schulze, Bert-Wolfgang},
title = {A new approach to the second order edge calculus},
series = {Journal of pseudo-differential operators and applications},
volume = {9},
journal = {Journal of pseudo-differential operators and applications},
number = {2},
publisher = {Springer},
address = {Basel},
issn = {1662-9981},
doi = {10.1007/s11868-017-0191-2},
pages = {265 -- 300},
year = {2018},
abstract = {We establish essential steps of an iterative approach to operator algebras, ellipticity and Fredholm property on stratified spaces with singularities of second order. We cover, in particular, corner-degenerate differential operators. Our constructions are focused on the case where no additional conditions of trace and potential type are posed, but this case works well and will be considered in a forthcoming paper as a conclusion of the present calculus.},
language = {en}
}
@article{KellerMuench2019,
author = {Keller, Matthias and M{\"u}nch, Florentin},
title = {A new discrete Hopf-Rinow theorem},
series = {Discrete Mathematics},
volume = {342},
journal = {Discrete Mathematics},
number = {9},
publisher = {Elsevier},
address = {Amsterdam},
issn = {0012-365X},
doi = {10.1016/j.disc.2019.03.014},
pages = {2751 -- 2757},
year = {2019},
abstract = {We prove a version of the Hopf-Rinow theorem with respect to path metrics on discrete spaces. The novel aspect is that we do not a priori assume local finiteness but isolate a local finiteness type condition, called essentially locally finite, that is indeed necessary. As a side product we identify the maximal weight, called the geodesic weight, generating the path metric in the situation when the space is complete with respect to any of the equivalent notions of completeness proven in the Hopf-Rinow theorem. As an application we characterize the graphs for which the resistance metric is a path metric induced by the graph structure.},
language = {en}
}
@article{MakhmudovMakhmudovTarkhanov2017,
author = {Makhmudov, K. O. and Makhmudov, O. I. and Tarkhanov, Nikolai Nikolaevich},
title = {A nonstandard Cauchy problem for the heat equation},
series = {Mathematical Notes},
volume = {102},
journal = {Mathematical Notes},
publisher = {Pleiades Publ.},
address = {New York},
issn = {0001-4346},
doi = {10.1134/S0001434617070264},
pages = {250 -- 260},
year = {2017},
abstract = {We consider the Cauchy problem for the heat equation in a cylinder C (T) = X x (0, T) over a domain X in R (n) , with data on a strip lying on the lateral surface. The strip is of the form S x (0, T), where S is an open subset of the boundary of X. The problem is ill-posed. Under natural restrictions on the configuration of S, we derive an explicit formula for solutions of this problem.},
language = {en}
}
@unpublished{MakhmudovMakhmudovTarkhanov2015,
author = {Makhmudov, K. O. and Makhmudov, O. I. and Tarkhanov, Nikolai Nikolaevich},
title = {A nonstandard Cauchy problem for the heat equation},
volume = {4},
number = {11},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-83830},
pages = {14},
year = {2015},
abstract = {We consider a Cauchy problem for the heat equation in a cylinder X x (0,T) over a domain X in the n-dimensional space with data on a strip lying on the lateral surface. The strip is of the form S x (0,T), where S is an open subset of the boundary of X. The problem is ill-posed. Under natural restrictions on the configuration of S we derive an explicit formula for solutions of this problem.},
language = {en}
}
@unpublished{Liero2006,
author = {Liero, Hannelore},
title = {A Note on : testing the Copula Based on Densities},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-49393},
year = {2006},
abstract = {We consider the problem of testing whether the density of a mul- tivariate random variable can be expressed by a prespecified copula function and the marginal densities. The proposed test procedure is based on the asymptotic normality of the properly standardized integrated squared distance between a multivariate kernel density estimator and an estimator of its expectation under the hypothesis. The test of independence is a special case of this approach.},
language = {en}
}
@article{KellerLiuPeyerimhoff2021,
author = {Keller, Matthias and Liu, Shiping and Peyerimhoff, Norbert},
title = {A note on eigenvalue bounds for non-compact manifolds},
series = {Mathematische Nachrichten},
volume = {294},
journal = {Mathematische Nachrichten},
number = {6},
publisher = {Wiley-VCH},
address = {Weinheim},
issn = {0025-584X},
doi = {10.1002/mana.201900209},
pages = {1134 -- 1139},
year = {2021},
abstract = {In this article we prove upper bounds for the Laplace eigenvalues lambda(k) below the essential spectrum for strictly negatively curved Cartan-Hadamard manifolds. Our bound is given in terms of k(2) and specific geometric data of the manifold. This applies also to the particular case of non-compact manifolds whose sectional curvature tends to -infinity, where no essential spectrum is present due to a theorem of Donnelly/Li. The result stands in clear contrast to Laplacians on graphs where such a bound fails to be true in general.},
language = {en}
}
@article{DimitrovaFernandesKoppitz2017,
author = {Dimitrova, Ilinka and Fernandes, Vitor H. and Koppitz, J{\"o}rg},
title = {A note on generators of the endomorphism semigroup of an infinite countable chain},
series = {Journal of Algebra and its Applications},
volume = {16},
journal = {Journal of Algebra and its Applications},
number = {2},
publisher = {World Scientific},
address = {Singapore},
issn = {0219-4988},
doi = {10.1142/S0219498817500311},
pages = {9},
year = {2017},
abstract = {In this note, we consider the semigroup O(X) of all order endomorphisms of an infinite chain X and the subset J of O(X) of all transformations alpha such that vertical bar Im(alpha)vertical bar = vertical bar X vertical bar. For an infinite countable chain X, we give a necessary and sufficient condition on X for O(X) = < J > to hold. We also present a sufficient condition on X for O(X) = < J > to hold, for an arbitrary infinite chain X.},
language = {en}
}
@article{HinzSchwarz2022,
author = {Hinz, Michael and Schwarz, Michael},
title = {A note on Neumann problems on graphs},
series = {Positivity},
volume = {26},
journal = {Positivity},
number = {4},
publisher = {Springer},
address = {Dordrecht},
issn = {1385-1292},
doi = {10.1007/s11117-022-00930-0},
pages = {23},
year = {2022},
abstract = {We discuss Neumann problems for self-adjoint Laplacians on (possibly infinite) graphs. Under the assumption that the heat semigroup is ultracontractive we discuss the unique solvability for non-empty subgraphs with respect to the vertex boundary and provide analytic and probabilistic representations for Neumann solutions. A second result deals with Neumann problems on canonically compactifiable graphs with respect to the Royden boundary and provides conditions for unique solvability and analytic and probabilistic representations.},
language = {en}
}
@unpublished{Camales2003,
author = {Camal{\`e}s, Renaud},
title = {A note on the ramified Cauchy problem},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26646},
year = {2003},
abstract = {In this paper, the ramified Cauchy problem in C² for operator with multiple characteristics of constant multiplicity and second member ramified around some analytic set is studied.},
language = {en}
}
@unpublished{NehringZessin2010,
author = {Nehring, Benjamin and Zessin, Hans},
title = {A path integral representation of the moment measures of the general ideal Bose gas},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-49635},
year = {2010},
abstract = {We reconsider the fundamental work of Fichtner ([2]) and exhibit the permanental structure of the ideal Bose gas again, using another approach which combines a characterization of infinitely divisible random measures (due to Kerstan,Kummer and Matthes [5, 6] and Mecke [8, 9]) with a decomposition of the moment measures into its factorial measures due to Krickeberg [4]. To be more precise, we exhibit the moment measures of all orders of the general ideal Bose gas in terms of certain path integrals. This representation can be considered as a point process analogue of the old idea of Symanzik [11] that local times and self-crossings of the Brownian motion can be used as a tool in quantum field theory. Behind the notion of a general ideal Bose gas there is a class of infinitely divisible point processes of all orders with a Levy-measure belonging to some large class of measures containing the one of the classical ideal Bose gas considered by Fichtner. It is well known that the calculation of moments of higher order of point processes are notoriously complicated. See for instance Krickeberg's calculations for the Poisson or the Cox process in [4].},
language = {en}
}
@article{MalassTarkhanov2020,
author = {Malass, Ihsane and Tarkhanov, Nikolaj Nikolaevič},
title = {A perturbation of the de Rham complex},
series = {Journal of Siberian Federal University : Mathematics \& Physics},
volume = {13},
journal = {Journal of Siberian Federal University : Mathematics \& Physics},
number = {5},
publisher = {Siberian Federal University},
address = {Krasnojarsk},
issn = {1997-1397},
doi = {10.17516/1997-1397-2020-13-5-519-532},
pages = {519 -- 532},
year = {2020},
abstract = {We consider a perturbation of the de Rham complex on a compact manifold with boundary. This perturbation goes beyond the framework of complexes, and so cohomology does not apply to it. On the other hand, its curvature is "small", hence there is a natural way to introduce an Euler characteristic and develop a Lefschetz theory for the perturbation. This work is intended as an attempt to develop a cohomology theory for arbitrary sequences of linear mappings.},
language = {en}
}
@unpublished{KellerRoellyValleriani2013,
author = {Keller, Peter and Roelly, Sylvie and Valleriani, Angelo},
title = {A quasi-random-walk to model a biological transport process},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-63582},
year = {2013},
abstract = {Transport Molecules play a crucial role for cell viability. Amongst others, linear motors transport cargos along rope-like structures from one location of the cell to another in a stochastic fashion. Thereby each step of the motor, either forwards or backwards, bridges a fixed distance. While moving along the rope the motor can also detach and is lost. We give here a mathematical formalization of such dynamics as a random process which is an extension of Random Walks, to which we add an absorbing state to model the detachment of the motor from the rope. We derive particular properties of such processes that have not been available before. Our results include description of the maximal distance reached from the starting point and the position from which detachment takes place. Finally, we apply our theoretical results to a concrete established model of the transport molecule Kinesin V.},
language = {en}
}
@article{FedchenkoTarkhanov2017,
author = {Fedchenko, Dmitry and Tarkhanov, Nikolai Nikolaevich},
title = {A Rado theorem for the porous medium equation},
series = {Boletin de la Sociedad Matem{\´a}tica Mexicana},
volume = {24},
journal = {Boletin de la Sociedad Matem{\´a}tica Mexicana},
number = {2},
publisher = {Springer},
address = {Cham},
issn = {1405-213X},
doi = {10.1007/s40590-017-0169-3},
pages = {427 -- 437},
year = {2017},
abstract = {We prove that if u is a locally Lipschitz continuous function on an open set chi subset of Rn + 1 satisfying the nonlinear heat equation partial derivative(t)u = Delta(vertical bar u vertical bar(p-1) u), p > 1, weakly away from the zero set u(-1) (0) in chi, then u is a weak solution to this equation in all of chi.},
language = {en}
}
@unpublished{LyTarkhanov2015,
author = {Ly, Ibrahim and Tarkhanov, Nikolai Nikolaevich},
title = {A Rad{\´o} theorem for p-harmonic functions},
volume = {4},
number = {3},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-71492},
pages = {10},
year = {2015},
abstract = {Let A be a nonlinear differential operator on an open set X in R^n and S a closed subset of X. Given a class F of functions in X, the set S is said to be removable for F relative to A if any weak solution of A (u) = 0 in the complement of S of class F satisfies this equation weakly in all of X. For the most extensively studied classes F we show conditions on S which guarantee that S is removable for F relative to A.},
language = {en}
}
@unpublished{FedchenkoTarkhanov2017,
author = {Fedchenko, Dmitry and Tarkhanov, Nikolai Nikolaevich},
title = {A Rad{\´o} Theorem for the Porous Medium Equation},
series = {Preprints des Instituts f{\"u}r Mathematik der Universit{\"a}t Potsdam},
volume = {6},
journal = {Preprints des Instituts f{\"u}r Mathematik der Universit{\"a}t Potsdam},
number = {1},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-102735},
pages = {12},
year = {2017},
abstract = {We prove that each locally Lipschitz continuous function satisfying the porous medium equation away from the set of its zeroes is actually a weak solution of this equation in the whole domain.},
language = {en}
}
@unpublished{FedosovSchulzeTarkhanov1998,
author = {Fedosov, Boris and Schulze, Bert-Wolfgang and Tarkhanov, Nikolai Nikolaevich},
title = {A remark on the index of symmetric operators},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25169},
year = {1998},
abstract = {We introduce a natural symmetry condition for a pseudodifferential operator on a manifold with cylindrical ends ensuring that the operator admits a doubling across the boundary. For such operators we prove an explicit index formula containing, apart from the Atiyah-Singer integral, a finite number of residues of the logarithmic derivative of the conormal symbol.},
language = {en}
}
@article{ChelkhLyTarkhanov2020,
author = {Chelkh, W. and Ly, Ibrahim and Tarkhanov, Nikolai},
title = {A remark on the Laplace transform},
series = {Siberian Mathematical Journal},
volume = {61},
journal = {Siberian Mathematical Journal},
number = {4},
publisher = {Consultants Bureau, Springer},
address = {New York},
issn = {0037-4466},
doi = {10.1134/S0037446620040151},
pages = {755 -- 762},
year = {2020},
abstract = {The study of the Cauchy problem for solutions of the heat equation in a cylindrical domain with data on the lateral surface by the Fourier method raises the problem of calculating the inverse Laplace transform of the entire function cos root z. This problem has no solution in the standard theory of the Laplace transform. We give an explicit formula for the inverse Laplace transform of cos root z using the theory of analytic functionals. This solution suits well to efficiently develop the regularization of solutions to Cauchy problems for parabolic equations with data on noncharacteristic surfaces.},
language = {en}
}
@unpublished{PolkovnikovTarkhanov2017,
author = {Polkovnikov, Alexander and Tarkhanov, Nikolai Nikolaevich},
title = {A Riemann-Hilbert problem for the Moisil-Teodorescu system},
volume = {6},
number = {3},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-397036},
pages = {31},
year = {2017},
abstract = {In a bounded domain with smooth boundary in R^3 we consider the stationary Maxwell equations for a function u with values in R^3 subject to a nonhomogeneous condition (u,v)_x = u_0 on the boundary, where v is a given vector field and u_0 a function on the boundary. We specify this problem within the framework of the Riemann-Hilbert boundary value problems for the Moisil-Teodorescu system. This latter is proved to satisfy the Shapiro-Lopaniskij condition if an only if the vector v is at no point tangent to the boundary. The Riemann-Hilbert problem for the Moisil-Teodorescu system fails to possess an adjoint boundary value problem with respect to the Green formula, which satisfies the Shapiro-Lopatinskij condition. We develop the construction of Green formula to get a proper concept of adjoint boundary value problem.},
language = {en}
}
@article{HanischLudewig2022,
author = {Hanisch, Florian and Ludewig, Matthias},
title = {A rigorous construction of the supersymmetric path integral associated to a compact spin manifold},
series = {Communications in mathematical physics},
volume = {391},
journal = {Communications in mathematical physics},
number = {3},
publisher = {Springer},
address = {Berlin ; Heidelberg},
issn = {0010-3616},
doi = {10.1007/s00220-022-04336-7},
pages = {1209 -- 1239},
year = {2022},
abstract = {We give a rigorous construction of the path integral in N = 1/2 supersymmetry as an integral map for differential forms on the loop space of a compact spin manifold. It is defined on the space of differential forms which can be represented by extended iterated integrals in the sense of Chen and Getzler-Jones-Petrack. Via the iterated integral map, we compare our path integral to the non-commutative loop space Chern character of Guneysu and the second author. Our theory provides a rigorous background to various formal proofs of the Atiyah-Singer index theorem for twisted Dirac operators using supersymmetric path integrals, as investigated by Alvarez-Gaume, Atiyah, Bismut and Witten.},
language = {en}
}
@article{KucharskiErgintavAhmadetal.2019,
author = {Kucharski, Maciej and Ergintav, Arzu and Ahmad, Wael Abdullah and Krstić, Miloš and Ng, Herman Jalli and Kissinger, Dietmar},
title = {A Scalable 79-GHz Radar Platform Based on Single-Channel Transceivers},
series = {IEEE Transactions on Microwave Theory and Techniques},
volume = {67},
journal = {IEEE Transactions on Microwave Theory and Techniques},
number = {9},
publisher = {Inst. of Electr. and Electronics Engineers},
address = {Piscataway},
issn = {0018-9480},
doi = {10.1109/TMTT.2019.2914104},
pages = {3882 -- 3896},
year = {2019},
abstract = {This paper presents a scalable E-band radar platform based on single-channel fully integrated transceivers (TRX) manufactured using 130-nm silicon-germanium (SiGe) BiCMOS technology. The TRX is suitable for flexible radar systems exploiting massive multiple-input-multipleoutput (MIMO) techniques for multidimensional sensing. A fully integrated fractional-N phase-locked loop (PLL) comprising a 39.5-GHz voltage-controlled oscillator is used to generate wideband frequency-modulated continuous-wave (FMCW) chirp for E-band radar front ends. The TRX is equipped with a vector modulator (VM) for high-speed carrier modulation and beam-forming techniques. A single TRX achieves 19.2-dBm maximum output power and 27.5-dB total conversion gain with input-referred 1-dB compression point of -10 dBm. It consumes 220 mA from 3.3-V supply and occupies 3.96 mm(2) silicon area. A two-channel radar platform based on full-custom TRXs and PLL was fabricated to demonstrate high-precision and high-resolution FMCW sensing. The radar enables up to 10-GHz frequency ramp generation in 74-84-GHz range, which results in 1.5-cm spatial resolution. Due to high output power, thus high signal-to-noise ratio (SNR), a ranging precision of 7.5 mu m for a target at 2 m was achieved. The proposed architecture supports scalable multichannel applications for automotive FMCW using a single local oscillator (LO).},
language = {en}
}
@unpublished{SchulzeNazaikinskiiSternin1998,
author = {Schulze, Bert-Wolfgang and Nazaikinskii, Vladimir and Sternin, Boris},
title = {A semiclassical quantization on manifolds with singularities and the Lefschetz Formula for Elliptic Operators},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25296},
year = {1998},
abstract = {For general endomorphisms of elliptic complexes on manifolds with conical singularities, the semiclassical asymptotics of the Atiyah-Bott-Lefschetz number is calculated in terms of fixed points of the corresponding canonical transformation of the symplectic space.},
language = {en}
}
@unpublished{Schrohe2000,
author = {Schrohe, Elmar},
title = {A short introduction to Boutet de Monvel's calculus},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25696},
year = {2000},
abstract = {This paper provides an introduction to Boutet de Monvel's calculus on the half-space IRn (positiv) in the framework of a pseudodifferential calculus with operator-valued symbols.},
language = {en}
}
@unpublished{Tarkhanov2012,
author = {Tarkhanov, Nikolai Nikolaevich},
title = {A simple numerical approach to the Riemann hypothesis},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57645},
year = {2012},
abstract = {The Riemann hypothesis is equivalent to the fact the the reciprocal function 1/zeta (s) extends from the interval (1/2,1) to an analytic function in the quarter-strip 1/2 < Re s < 1 and Im s > 0. Function theory allows one to rewrite the condition of analytic continuability in an elegant form amenable to numerical experiments.},
language = {en}
}
@unpublished{FlandoliHoegele2014,
author = {Flandoli, Franco and H{\"o}gele, Michael},
title = {A solution selection problem with small stable perturbations},
volume = {3},
number = {8},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71205},
pages = {43},
year = {2014},
abstract = {The zero-noise limit of differential equations with singular coefficients is investigated for the first time in the case when the noise is a general alpha-stable process. It is proved that extremal solutions are selected and the probability of selection is computed. Detailed analysis of the characteristic function of an exit time form on the half-line is performed, with a suitable decomposition in small and large jumps adapted to the singular drift.},
language = {en}
}
@unpublished{Tarkhanov2015,
author = {Tarkhanov, Nikolai Nikolaevich},
title = {A spectral theorem for deformation quantisation},
volume = {4},
number = {4},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-72425},
pages = {8},
year = {2015},
abstract = {We present a construction of the eigenstate at a noncritical level of the Hamiltonian function. Moreover, we evaluate the contributions of Morse critical points to the spectral decomposition.},
language = {en}
}
@article{Zoeller2018,
author = {Z{\"o}ller, Gert},
title = {A statistical model for earthquake recurrence based on the assimilation of paleoseismicity, historic seismicity, and instrumental seismicity},
series = {Journal of geophysical research : Solid earth},
volume = {123},
journal = {Journal of geophysical research : Solid earth},
number = {6},
publisher = {American Geophysical Union},
address = {Washington},
issn = {2169-9313},
doi = {10.1029/2017JB015099},
pages = {4906 -- 4921},
year = {2018},
abstract = {Paleoearthquakes and historic earthquakes are the most important source of information for the estimation of long-term earthquake recurrence intervals in fault zones, because corresponding sequences cover more than one seismic cycle. However, these events are often rare, dating uncertainties are enormous, and missing or misinterpreted events lead to additional problems. In the present study, I assume that the time to the next major earthquake depends on the rate of small and intermediate events between the large ones in terms of a clock change model. Mathematically, this leads to a Brownian passage time distribution for recurrence intervals. I take advantage of an earlier finding that under certain assumptions the aperiodicity of this distribution can be related to the Gutenberg-Richter b value, which can be estimated easily from instrumental seismicity in the region under consideration. In this way, both parameters of the Brownian passage time distribution can be attributed with accessible seismological quantities. This allows to reduce the uncertainties in the estimation of the mean recurrence interval, especially for short paleoearthquake sequences and high dating errors. Using a Bayesian framework for parameter estimation results in a statistical model for earthquake recurrence intervals that assimilates in a simple way paleoearthquake sequences and instrumental data. I present illustrative case studies from Southern California and compare the method with the commonly used approach of exponentially distributed recurrence times based on a stationary Poisson process.},
language = {en}
}
@article{StaniforthWoodReich2006,
author = {Staniforth, Andrew and Wood, Nigel and Reich, Sebastian},
title = {A time-staggered semi-Lagrangian discretization of the rotating shallow-water equations},
series = {Quarterly journal of the Royal Meteorological Society},
volume = {132},
journal = {Quarterly journal of the Royal Meteorological Society},
number = {621C},
publisher = {Wiley},
address = {Weinheim},
issn = {0035-9009},
doi = {10.1256/qj.06.30},
pages = {3107 -- 3116},
year = {2006},
abstract = {A time-staggered semi-Lagrangian discretization of the rotating shallow-water equations is proposed and analysed. Application of regularization to the geopotential field used in the momentum equations leads to an unconditionally stable scheme. The analysis, together with a fully nonlinear example application, suggests that this approach is a promising, efficient, and accurate alternative to traditional schemes.},
language = {en}
}
@article{Seyedhosseini2022,
author = {Seyedhosseini, Mehran},
title = {A variant of Roe algebras for spaces with cylindrical ends with applications in relative higher index theory},
series = {Journal of noncommutative geometry},
volume = {16},
journal = {Journal of noncommutative geometry},
number = {2},
publisher = {European Mathematical Society},
address = {Zurich},
issn = {1661-6952},
doi = {10.4171/JNCG/457},
pages = {595 -- 624},
year = {2022},
abstract = {In this paper, we define a variant of Roe algebras for spaces with cylindrical ends and use this to study questions regarding existence and classification of metrics of positive scalar curvature on such manifolds which are collared on the cylindrical end. We discuss how our constructions are related to relative higher index theory as developed by Chang, Weinberger, and Yu and use this relationship to define higher rho-invariants for positive scalar curvature metrics on manifolds with boundary. This paves the way for the classification of these metrics. Finally, we use the machinery developed here to give a concise proof of a result of Schick and the author, which relates the relative higher index with indices defined in the presence of positive scalar curvature on the boundary.},
language = {en}
}
@article{EdlundGrisicSteenholdtetal.2019,
author = {Edlund, Helena and Grisic, Ana-Marija and Steenholdt, Casper and Ainsworth, Mark Andrew and Brynskov, Torn and Huisinga, Wilhelm and Kloft, Charlotte},
title = {Absence of Relationship Between Crohn's Disease Activity Index or C-Reactive Protein and Infliximab Exposure Calls for Objective Crohn's Disease Activity Measures for the Evaluation of Treatment Effects at Treatment Failure},
series = {Therapeutic drug monitoring : official journal of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology},
volume = {41},
journal = {Therapeutic drug monitoring : official journal of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology},
number = {2},
publisher = {Lippincott Williams \& Wilkins},
address = {Philadelphia},
issn = {0163-4356},
doi = {10.1097/FTD.0000000000000590},
pages = {235 -- 242},
year = {2019},
abstract = {Background: Circulating infliximab (IFX) concentrations correlate with clinical outcomes, forming the basis of the IFX concentration monitoring in patients with Crohn's disease. This study aims to investigate and refine the exposure-response relationship by linking the disease activity markers "Crohn's disease activity index" (CDAI) and C-reactive protein (CRP) to IFX exposure. In addition, we aim to explore the correlations between different disease markers and exposure metrics. Methods: Data from 47 Crohn's disease patients of a randomized controlled trial were analyzed post hoc. All patients had secondary treatment failure at inclusion and had received intensified IFX of 5 mg/kg every 4 weeks for up to 20 weeks. Graphical analyses were performed to explore exposure-response relationships. Metrics of exposure included area under the concentration-time curve (AUC) and trough concentrations (Cmin). Disease activity was measured by CDAI and CRP values, their change from baseline/last visit, and response/remission outcomes at week 12. Results: Although trends toward lower Cmin and lower AUC in nonresponders were observed, neither CDAI nor CRP showed consistent trends of lower disease activity with higher IFX exposure across the 30 evaluated relationships. As can be expected, Cmin and AUC were strongly correlated with each other. Contrarily, the disease activity markers were only weakly correlated with each other. Conclusions: No significant relationship between disease activity, as evaluated by CDAI or CRP, and IFX exposure was identified. AUC did not add benefit compared with Cmin. These findings support the continued use of Cmin and call for stringent objective disease activity (bio-)markers (eg, endoscopy) to form the basis of personalized IFX therapy for Crohn's disease patients with IFX treatment failure.},
language = {en}
}
@article{GuggenbergerChechkinMetzler2022,
author = {Guggenberger, Tobias and Chechkin, Aleksei and Metzler, Ralf},
title = {Absence of stationary states and non-Boltzmann distributions of fractional Brownian motion in shallow external potentials},
series = {New journal of physics : the open-access journal for physics},
volume = {24},
journal = {New journal of physics : the open-access journal for physics},
number = {7},
publisher = {Dt. Physikalische Ges.},
address = {[Bad Honnef]},
issn = {1367-2630},
doi = {10.1088/1367-2630/ac7b3c},
pages = {18},
year = {2022},
abstract = {We study the diffusive motion of a particle in a subharmonic potential of the form U(x) = |x|( c ) (0 < c < 2) driven by long-range correlated, stationary fractional Gaussian noise xi ( alpha )(t) with 0 < alpha <= 2. In the absence of the potential the particle exhibits free fractional Brownian motion with anomalous diffusion exponent alpha. While for an harmonic external potential the dynamics converges to a Gaussian stationary state, from extensive numerical analysis we here demonstrate that stationary states for shallower than harmonic potentials exist only as long as the relation c > 2(1 - 1/alpha) holds. We analyse the motion in terms of the mean squared displacement and (when it exists) the stationary probability density function. Moreover we discuss analogies of non-stationarity of Levy flights in shallow external potentials.},
language = {en}
}
@article{JansenKolesnikov2020,
author = {Jansen, Sabine and Kolesnikov, Leonid},
title = {Activity expansions for Gibbs correlation functions},
series = {Lectures in pure and applied mathematics},
journal = {Lectures in pure and applied mathematics},
number = {6},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
isbn = {978-3-86956-485-2},
issn = {2199-4951},
doi = {10.25932/publishup-47212},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472121},
pages = {145 -- 154},
year = {2020},
language = {en}
}
@article{CarpentierKloppLoeffleretal.2018,
author = {Carpentier, Alexandra and Klopp, Olga and L{\"o}ffler, Matthias and Nickl, Richard},
title = {Adaptive confidence sets for matrix completion},
series = {Bernoulli : official journal of the Bernoulli Society for Mathematical Statistics and Probability},
volume = {24},
journal = {Bernoulli : official journal of the Bernoulli Society for Mathematical Statistics and Probability},
number = {4A},
publisher = {International Statistical Institute},
address = {Voorburg},
issn = {1350-7265},
doi = {10.3150/17-BEJ933},
pages = {2429 -- 2460},
year = {2018},
abstract = {In the present paper, we study the problem of existence of honest and adaptive confidence sets for matrix completion. We consider two statistical models: the trace regression model and the Bernoulli model. In the trace regression model, we show that honest confidence sets that adapt to the unknown rank of the matrix exist even when the error variance is unknown. Contrary to this, we prove that in the Bernoulli model, honest and adaptive confidence sets exist only when the error variance is known a priori. In the course of our proofs, we obtain bounds for the minimax rates of certain composite hypothesis testing problems arising in low rank inference.},
language = {en}
}
@unpublished{JunkerSchrohe2001,
author = {Junker, Wolfgang and Schrohe, Elmar},
title = {Adiabatic vacuum states on general spacetime manifolds : definition, construction, and physical properties},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26100},
year = {2001},
abstract = {Adiabatic vacuum states are a well-known class of physical states for linear quantum fields n Robertson-Walker spacetimes. We extend the definition of adiabatic vacua to general spacetime manifolds by using the notion of the Sobolev wavefront set. This definition is also applicable to interacting field theories. Hadamard states form a special subclass of the adiabatic vacua. We analyze physical properties of adiabatic vacuum representations of the Klein-Gordon field on globally hyperbolic spacetme manifolds (factoriality, quasiequivalence, local definteness, Haag duality) and construct them explicitly, if the manifold has a compact Cauchy surface.},
language = {en}
}
@phdthesis{Hecher2021,
author = {Hecher, Markus},
title = {Advanced tools and methods for treewidth-based problem solving},
doi = {10.25932/publishup-51251},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-512519},
school = {Universit{\"a}t Potsdam},
pages = {xv, 184},
year = {2021},
abstract = {In the last decades, there was a notable progress in solving the well-known Boolean satisfiability (Sat) problem, which can be witnessed by powerful Sat solvers. One of the reasons why these solvers are so fast are structural properties of instances that are utilized by the solver's interna. This thesis deals with the well-studied structural property treewidth, which measures the closeness of an instance to being a tree. In fact, there are many problems parameterized by treewidth that are solvable in polynomial time in the instance size when parameterized by treewidth. In this work, we study advanced treewidth-based methods and tools for problems in knowledge representation and reasoning (KR). Thereby, we provide means to establish precise runtime results (upper bounds) for canonical problems relevant to KR. Then, we present a new type of problem reduction, which we call decomposition-guided (DG) that allows us to precisely monitor the treewidth when reducing from one problem to another problem. This new reduction type will be the basis for a long-open lower bound result for quantified Boolean formulas and allows us to design a new methodology for establishing runtime lower bounds for problems parameterized by treewidth. Finally, despite these lower bounds, we provide an efficient implementation of algorithms that adhere to treewidth. Our approach finds suitable abstractions of instances, which are subsequently refined in a recursive fashion, and it uses Sat solvers for solving subproblems. It turns out that our resulting solver is quite competitive for two canonical counting problems related to Sat.},
language = {en}
}
@article{GarbunoInigoNueskenReich2020,
author = {Garbuno-Inigo, Alfredo and N{\"u}sken, Nikolas and Reich, Sebastian},
title = {Affine invariant interacting Langevin dynamics for Bayesian inference},
series = {SIAM journal on applied dynamical systems},
volume = {19},
journal = {SIAM journal on applied dynamical systems},
number = {3},
publisher = {Society for Industrial and Applied Mathematics},
address = {Philadelphia},
issn = {1536-0040},
doi = {10.1137/19M1304891},
pages = {1633 -- 1658},
year = {2020},
abstract = {We propose a computational method (with acronym ALDI) for sampling from a given target distribution based on first-order (overdamped) Langevin dynamics which satisfies the property of affine invariance. The central idea of ALDI is to run an ensemble of particles with their empirical covariance serving as a preconditioner for their underlying Langevin dynamics. ALDI does not require taking the inverse or square root of the empirical covariance matrix, which enables application to high-dimensional sampling problems. The theoretical properties of ALDI are studied in terms of nondegeneracy and ergodicity. Furthermore, we study its connections to diffusion on Riemannian manifolds and Wasserstein gradient flows. Bayesian inference serves as a main application area for ALDI. In case of a forward problem with additive Gaussian measurement errors, ALDI allows for a gradient-free approximation in the spirit of the ensemble Kalman filter. A computational comparison between gradient-free and gradient-based ALDI is provided for a PDE constrained Bayesian inverse problem.},
language = {en}
}
@unpublished{KleinLeonardRosenberger2012,
author = {Klein, Markus and L{\´e}onard, Christian and Rosenberger, Elke},
title = {Agmon-type estimates for a class of jump processes},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-56995},
year = {2012},
abstract = {In the limit we analyze the generators of families of reversible jump processes in the n-dimensional space associated with a class of symmetric non-local Dirichlet forms and show exponential decay of the eigenfunctions. The exponential rate function is a Finsler distance, given as solution of certain eikonal equation. Fine results are sensitive to the rate functions being twice differentiable or just Lipschitz. Our estimates are similar to the semiclassical Agmon estimates for differential operators of second order. They generalize and strengthen previous results on the lattice.},
language = {en}
}
@article{GuoPaychaZhang2017,
author = {Guo, Li and Paycha, Sylvie and Zhang, Bin},
title = {Algebraic Birkhoff factorization and the Euler-Maclaurin formula on cones},
series = {Duke mathematical journal},
volume = {166},
journal = {Duke mathematical journal},
number = {3},
publisher = {Duke Univ. Press},
address = {Durham},
issn = {0012-7094},
doi = {10.1215/00127094-3715303},
pages = {537 -- 571},
year = {2017},
abstract = {We equip the space of lattice cones with a coproduct which makes it a cograded, coaugmented, connnected coalgebra. The exponential generating sum and exponential generating integral on lattice cones can be viewed as linear maps on this space with values in the space of meromorphic germs with linear poles at zero. We investigate the subdivision properties-reminiscent of the inclusion-exclusion principle for the cardinal on finite sets-of such linear maps and show that these properties are compatible with the convolution quotient of maps on the coalgebra. Implementing the algebraic Birkhoff factorization procedure on the linear maps under consideration, we factorize the exponential generating sum as a convolution quotient of two maps, with each of the maps in the factorization satisfying a subdivision property. A direct computation shows that the polar decomposition of the exponential generating sum on a smooth lattice cone yields an Euler-Maclaurin formula. The compatibility with subdivisions of the convolution quotient arising in the algebraic Birkhoff factorization then yields the Euler-Maclaurin formula for any lattice cone. This provides a simple formula for the interpolating factor by means of a projection formula.},
language = {en}
}
@phdthesis{Sareeto2024,
author = {Sareeto, Apatsara},
title = {Algebraic properties of a subsemigroup of the symmetric inverse semigroup},
school = {Universit{\"a}t Potsdam},
pages = {92},
year = {2024},
language = {en}
}
@misc{Reich1980,
author = {Reich, Sebastian},
title = {Algebrodifferentialgleichungen und Vektorfelder auf Mannigfaltigkeiten},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-47290},
year = {1980},
abstract = {In diesem Beitrag wird der Zusammenhang zwischen Algebrodifferentialgleichungen (ADGL) und Vektorfeldern auf Mannigfaltigkeiten untersucht. Dazu wird zun{\"a}chst der Begriff der regul{\"a}ren ADGL eingef{\"u}hrt, wobei unter eirter regul{\"a}ren ADGL eine ADGL verstanden wird, deren L{\"o}sungsmenge identisch mit der L{\"o}sungsmenge eines Vektorfeldes ist. Ausgehend von bekannten Aussagen {\"u}ber die L{\"o}sungsmenge eines Vektorfeldes werden analoge Aussagen f{\"u}r die L{\"o}sungsmenge einer regul{\"a}ren ADGL abgeleitet. Es wird eine Reduktionsmethode angegeben, die auf ein Kriterium f{\"u}r die Begularit{\"a}t einer ADGL und auf die Definition des Index einer nichtlinearen ADGL f{\"u}hrt. Außerdem wird gezeigt, daß beliebige Vektorfelder durch regul{\"a}re ADGL so realisiert werden k{\"o}nnen, daß die L{\"o}sungsmenge des Vektorfeldes mit der der realisierenden ADGL identisch ist. Abschließend werden die f{\"u}r autonome ADGL gewonnenen Aussagen auf den Fall der nichtautonomen ADGL {\"u}bertragen.},
language = {de}
}
@unpublished{Schulze1999,
author = {Schulze, Bert-Wolfgang},
title = {An algebra of boundary value problems not requiring Shapiro-Lopatinskil conditions},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25596},
year = {1999},
abstract = {We construct an algebra of pseudo-differential boundary value problems that contains the classical Shapiro-Lopatinskij elliptic problems as well as all differential elliptic problems of Dirac type with APS boundary conditions, together with their parametrices. Global pseudo-differential projections on the boundary are used to define ellipticity and to show the Fredholm property in suitable scales of spaces.},
language = {en}
}
@unpublished{ManicciaSchulze2002,
author = {Maniccia, L. and Schulze, Bert-Wolfgang},
title = {An algebra of meromorphic corner symbols},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26360},
year = {2002},
abstract = {Operators on manifolds with corners that have base configurations with geometric singularities can be analysed in the frame of a conormal symbolic structure which is in spirit similar to the one for conical singularities of Kondrat'ev's work. Solvability of elliptic equations and asymptotics of solutions are determined by meromorphic conormal symbols. We study the case when the base has edge singularities which is a natural assumption in a number of applications. There are new phenomena, caused by a specific kind of higher degeneracy of the underlying symbols. We introduce an algebra of meromorphic edge operators that depend on complex parameters and investigate meromorphic inverses in the parameter-dependent elliptic case. Among the examples are resolvents of elliptic differential operators on manifolds with edges.},
language = {en}
}
@article{ClavierGuoPaychaetal.2019,
author = {Clavier, Pierre J. and Guo, Li and Paycha, Sylvie and Zhang, Bin},
title = {An algebraic formulation of the locality principle in renormalisation},
series = {European Journal of Mathematics},
volume = {5},
journal = {European Journal of Mathematics},
number = {2},
publisher = {Springer},
address = {Cham},
issn = {2199-675X},
doi = {10.1007/s40879-018-0255-8},
pages = {356 -- 394},
year = {2019},
abstract = {We study the mathematical structure underlying the concept of locality which lies at the heart of classical and quantum field theory, and develop a machinery used to preserve locality during the renormalisation procedure. Viewing renormalisation in the framework of Connes and Kreimer as the algebraic Birkhoff factorisation of characters on a Hopf algebra with values in a Rota-Baxter algebra, we build locality variants of these algebraic structures, leading to a locality variant of the algebraic Birkhoff factorisation. This provides an algebraic formulation of the conservation of locality while renormalising. As an application in the context of the Euler-Maclaurin formula on lattice cones, we renormalise the exponential generating function which sums over the lattice points in a lattice cone. As a consequence, for a suitable multivariate regularisation, renormalisation from the algebraic Birkhoff factorisation amounts to composition by a projection onto holomorphic multivariate germs.},
language = {en}
}
@article{MeraTarkhanov2022,
author = {Mera, Azal Jaafar Musa and Tarkhanov, Nikolai},
title = {An elliptic equation of finite index in a domain},
series = {Boletin de la Sociedad Matem{\´a}tica Mexicana},
volume = {28},
journal = {Boletin de la Sociedad Matem{\´a}tica Mexicana},
number = {2},
publisher = {Springer International},
address = {New York [u.a.]},
issn = {1405-213X},
doi = {10.1007/s40590-022-00442-7},
pages = {10},
year = {2022},
abstract = {We give an example of first order elliptic equation for a complex-valued function in a plane domain which has a finite number of linearly independent solutions for any right-hand side. No boundary value conditions are thus required.},
language = {en}
}
@misc{RoellyDaiPra2004,
author = {Roelly, Sylvie and Dai Pra, Paolo},
title = {An existence result for infinite-dimensional Brownian diffusions with non- regular and non Markovian drift},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-6684},
year = {2004},
abstract = {We prove in this paper an existence result for infinite-dimensional stationary interactive Brownian diffusions. The interaction is supposed to be small in the norm ||.||∞ but otherwise is very general, being possibly non-regular and non-Markovian. Our method consists in using the characterization of such diffusions as space-time Gibbs fields so that we construct them by space-time cluster expansions in the small coupling parameter.},
language = {en}
}
@article{HoudebertZass2022,
author = {Houdebert, Pierre and Zass, Alexander},
title = {An explicit Dobrushin uniqueness region for Gibbs point processes with repulsive interactions},
series = {Journal of applied probability / Applied Probability Trust},
volume = {59},
journal = {Journal of applied probability / Applied Probability Trust},
number = {2},
publisher = {Cambridge Univ. Press},
address = {Cambridge},
issn = {0021-9002},
doi = {10.1017/jpr.2021.70},
pages = {541 -- 555},
year = {2022},
abstract = {We present a uniqueness result for Gibbs point processes with interactions that come from a non-negative pair potential; in particular, we provide an explicit uniqueness region in terms of activity z and inverse temperature beta. The technique used relies on applying to the continuous setting the classical Dobrushin criterion. We also present a comparison to the two other uniqueness methods of cluster expansion and disagreement percolation, which can also be applied for this type of interaction.},
language = {en}
}
@unpublished{DereudreMazzonettoRoelly2015,
author = {Dereudre, David and Mazzonetto, Sara and Roelly, Sylvie},
title = {An explicit representation of the transition densities of the skew Brownian motion with drift and two semipermeable barriers},
volume = {4},
number = {9},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-80613},
pages = {23},
year = {2015},
abstract = {In this paper we obtain an explicit representation of the transition density of the one-dimensional skew Brownian motion with (a constant drift and) two semipermeable barriers. Moreover we propose a rejection method to simulate this density in an exact way.},
language = {en}
}
@unpublished{MakhmudovTarkhanov2013,
author = {Makhmudov, Olimdjan and Tarkhanov, Nikolai Nikolaevich},
title = {An extremal problem related to analytic continuation},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-63634},
year = {2013},
abstract = {We show that the usual variational formulation of the problem of analytic continuation from an arc on the boundary of a plane domain does not lead to a relaxation of this overdetermined problem. To attain such a relaxation, we bound the domain of the functional, thus changing the Euler equations.},
language = {en}
}
@article{KellerPinchoverPogorzelski2018,
author = {Keller, Matthias and Pinchover, Yehuda and Pogorzelski, Felix},
title = {An improved discrete hardy inequality},
series = {The American mathematical monthly : an official publication of the Mathematical Association of America},
volume = {125},
journal = {The American mathematical monthly : an official publication of the Mathematical Association of America},
number = {4},
publisher = {Taylor \& Francis Group},
address = {Philadelphia},
issn = {0002-9890},
doi = {10.1080/00029890.2018.1420995},
pages = {347 -- 350},
year = {2018},
abstract = {In this note, we prove an improvement of the classical discrete Hardy inequality. Our improved Hardy-type inequality holds with a weight w which is strictly greater than the classical Hardy weight w(H)(n) : 1/(2n)(2), where N.},
language = {en}
}
@unpublished{FedchenkoTarkhanov2014,
author = {Fedchenko, Dmitry and Tarkhanov, Nikolai Nikolaevich},
title = {An index formula for Toeplitz operators},
volume = {3},
number = {12},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72499},
pages = {24},
year = {2014},
abstract = {We prove a Fedosov index formula for the index of Toeplitz operators connected with the Hardy space of solutions to an elliptic system of first order partial differential equations in a bounded domain of Euclidean space with infinitely differentiable boundary.},
language = {en}
}
@article{BaerStrohmaier2019,
author = {B{\"a}r, Christian and Strohmaier, Alexander},
title = {An index theorem for Lorentzian manifolds with compact spacelike Cauchy boundary},
series = {American Journal of Mathematics},
volume = {141},
journal = {American Journal of Mathematics},
number = {5},
publisher = {Johns Hopkins Univ. Press},
address = {Baltimore},
issn = {0002-9327},
doi = {10.1353/ajm.2019.0037},
pages = {1421 -- 1455},
year = {2019},
abstract = {We show that the Dirac operator on a compact globally hyperbolic Lorentzian spacetime with spacelike Cauchy boundary is a Fredholm operator if appropriate boundary conditions are imposed. We prove that the index of this operator is given by the same expression as in the index formula of Atiyah-Patodi-Singer for Riemannian manifolds with boundary. The index is also shown to equal that of a certain operator constructed from the evolution operator and a spectral projection on the boundary. In case the metric is of product type near the boundary a Feynman parametrix is constructed.},
language = {en}
}
@unpublished{AizenbergTarkhanov2014,
author = {Aizenberg, Lev A. and Tarkhanov, Nikolai Nikolaevich},
title = {An integral formula for the number of lattice points in a domain},
volume = {3},
number = {3},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70453},
pages = {7},
year = {2014},
abstract = {Using the multidimensional logarithmic residue we show a simple formula for the difference between the number of integer points in a bounded domain of R^n and the volume of this domain. The difference proves to be the integral of an explicit differential form over the boundary of the domain.},
language = {en}
}
@misc{SerthPodlesnyBornsteinetal.2017,
author = {Serth, Sebastian and Podlesny, Nikolai and Bornstein, Marvin and Lindemann, Jan and Latt, Johanna and Selke, Jan and Schlosser, Rainer and Boissier, Martin and Uflacker, Matthias},
title = {An interactive platform to simulate dynamic pricing competition on online marketplaces},
series = {2017 IEEE 21st International Enterprise Distributed Object Computing Conference (EDOC)},
journal = {2017 IEEE 21st International Enterprise Distributed Object Computing Conference (EDOC)},
publisher = {Institute of Electrical and Electronics Engineers},
address = {New York},
isbn = {978-1-5090-3045-3},
issn = {2325-6354},
doi = {10.1109/EDOC.2017.17},
pages = {61 -- 66},
year = {2017},
abstract = {E-commerce marketplaces are highly dynamic with constant competition. While this competition is challenging for many merchants, it also provides plenty of opportunities, e.g., by allowing them to automatically adjust prices in order to react to changing market situations. For practitioners however, testing automated pricing strategies is time-consuming and potentially hazardously when done in production. Researchers, on the other side, struggle to study how pricing strategies interact under heavy competition. As a consequence, we built an open continuous time framework to simulate dynamic pricing competition called Price Wars. The microservice-based architecture provides a scalable platform for large competitions with dozens of merchants and a large random stream of consumers. Our platform stores each event in a distributed log. This allows to provide different performance measures enabling users to compare profit and revenue of various repricing strategies in real-time. For researchers, price trajectories are shown which ease evaluating mutual price reactions of competing strategies. Furthermore, merchants can access historical marketplace data and apply machine learning. By providing a set of customizable, artificial merchants, users can easily simulate both simple rule-based strategies as well as sophisticated data-driven strategies using demand learning to optimize their pricing strategies.},
language = {en}
}
@book{Pilipenko2014,
author = {Pilipenko, Andrey},
title = {An introduction to stochastic differential equations with reflection},
series = {Lectures in pure and applied mathematics},
journal = {Lectures in pure and applied mathematics},
number = {1},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
isbn = {978-3-86956-297-1},
issn = {2199-4951},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70782},
publisher = {Universit{\"a}t Potsdam},
pages = {ix, 75},
year = {2014},
abstract = {These lecture notes are intended as a short introduction to diffusion processes on a domain with a reflecting boundary for graduate students, researchers in stochastic analysis and interested readers. Specific results on stochastic differential equations with reflecting boundaries such as existence and uniqueness, continuity and Markov properties, relation to partial differential equations and submartingale problems are given. An extensive list of references to current literature is included. This book has its origins in a mini-course the author gave at the University of Potsdam and at the Technical University of Berlin in Winter 2013.},
language = {en}
}
@phdthesis{Abed2010,
author = {Abed, Jamil},
title = {An iterative approach to operators on manifolds with singularities},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-44757},
school = {Universit{\"a}t Potsdam},
year = {2010},
abstract = {We establish elements of a new approach to ellipticity and parametrices within operator algebras on manifolds with higher singularities, only based on some general axiomatic requirements on parameter-dependent operators in suitable scales of spaes. The idea is to model an iterative process with new generations of parameter-dependent operator theories, together with new scales of spaces that satisfy analogous requirements as the original ones, now on a corresponding higher level. The "full" calculus involves two separate theories, one near the tip of the corner and another one at the conical exit to infinity. However, concerning the conical exit to infinity, we establish here a new concrete calculus of edge-degenerate operators which can be iterated to higher singularities.},
language = {en}
}
@article{CarpentierKim2018,
author = {Carpentier, Alexandra and Kim, Arlene K. H.},
title = {An iterative hard thresholding estimator for low rank matrix recovery with explicit limiting distribution},
series = {Statistica Sinica},
volume = {28},
journal = {Statistica Sinica},
number = {3},
publisher = {Statistica Sinica, Institute of Statistical Science, Academia Sinica},
address = {Taipei},
issn = {1017-0405},
doi = {10.5705/ss.202016.0103},
pages = {1371 -- 1393},
year = {2018},
abstract = {We consider the problem of low rank matrix recovery in a stochastically noisy high-dimensional setting. We propose a new estimator for the low rank matrix, based on the iterative hard thresholding method, that is computationally efficient and simple. We prove that our estimator is optimal in terms of the Frobenius risk and in terms of the entry-wise risk uniformly over any change of orthonormal basis, allowing us to provide the limiting distribution of the estimator. When the design is Gaussian, we prove that the entry-wise bias of the limiting distribution of the estimator is small, which is of interest for constructing tests and confidence sets for low-dimensional subsets of entries of the low rank matrix.},
language = {en}
}
@unpublished{ShlapunovTarkhanov2016,
author = {Shlapunov, Alexander and Tarkhanov, Nikolai Nikolaevich},
title = {An open mapping theorem for the Navier-Stokes equations},
volume = {5},
number = {10},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-98687},
pages = {80},
year = {2016},
abstract = {We consider the Navier-Stokes equations in the layer R^n x [0,T] over R^n with finite T > 0. Using the standard fundamental solutions of the Laplace operator and the heat operator, we reduce the Navier-Stokes equations to a nonlinear Fredholm equation of the form (I+K) u = f, where K is a compact continuous operator in anisotropic normed H{\"o}lder spaces weighted at the point at infinity with respect to the space variables. Actually, the weight function is included to provide a finite energy estimate for solutions to the Navier-Stokes equations for all t in [0,T]. On using the particular properties of the de Rham complex we conclude that the Fr{\´e}chet derivative (I+K)' is continuously invertible at each point of the Banach space under consideration and the map I+K is open and injective in the space. In this way the Navier-Stokes equations prove to induce an open one-to-one mapping in the scale of H{\"o}lder spaces.},
language = {en}
}
@article{ShlapunovTarchanov2021,
author = {Shlapunov, Alexander and Tarchanov, Nikolaj Nikolaevič},
title = {An open mapping theorem for the Navier-Stokes type equations associated with the de Rham complex over R-n},
series = {Siberian electronic mathematical reports = Sibirskie ėlektronnye matematičeskie izvestija},
volume = {18},
journal = {Siberian electronic mathematical reports = Sibirskie ėlektronnye matematičeskie izvestija},
number = {2},
publisher = {Institut Matematiki Imeni S. L. Soboleva},
address = {Novosibirsk},
issn = {1813-3304},
doi = {10.33048/semi.2021.18.108},
pages = {1433 -- 1466},
year = {2021},
abstract = {We consider an initial problem for the Navier-Stokes type equations associated with the de Rham complex over R-n x[0, T], n >= 3, with a positive time T. We prove that the problem induces an open injective mappings on the scales of specially constructed function spaces of Bochner-Sobolev type. In particular, the corresponding statement on the intersection of these classes gives an open mapping theorem for smooth solutions to the Navier-Stokes equations.},
language = {en}
}
@misc{WiljesTong2020,
author = {Wiljes, Jana de and Tong, Xin T.},
title = {Analysis of a localised nonlinear ensemble Kalman Bucy filter with complete and accurate observations},
series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
volume = {33},
journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
number = {9},
publisher = {IOP Publ.},
address = {Bristol},
issn = {1866-8372},
doi = {10.25932/publishup-54041},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-540417},
pages = {4752 -- 4782},
year = {2020},
abstract = {Concurrent observation technologies have made high-precision real-time data available in large quantities. Data assimilation (DA) is concerned with how to combine this data with physical models to produce accurate predictions. For spatial-temporal models, the ensemble Kalman filter with proper localisation techniques is considered to be a state-of-the-art DA methodology. This article proposes and investigates a localised ensemble Kalman Bucy filter for nonlinear models with short-range interactions. We derive dimension-independent and component-wise error bounds and show the long time path-wise error only has logarithmic dependence on the time range. The theoretical results are verified through some simple numerical tests.},
language = {en}
}
@article{WiljesTong2020,
author = {Wiljes, Jana de and Tong, Xin T.},
title = {Analysis of a localised nonlinear ensemble Kalman Bucy filter with complete and accurate observations},
series = {Nonlinearity},
volume = {33},
journal = {Nonlinearity},
number = {9},
publisher = {IOP Publ.},
address = {Bristol},
issn = {0951-7715},
doi = {10.1088/1361-6544/ab8d14},
pages = {4752 -- 4782},
year = {2020},
abstract = {Concurrent observation technologies have made high-precision real-time data available in large quantities. Data assimilation (DA) is concerned with how to combine this data with physical models to produce accurate predictions. For spatial-temporal models, the ensemble Kalman filter with proper localisation techniques is considered to be a state-of-the-art DA methodology. This article proposes and investigates a localised ensemble Kalman Bucy filter for nonlinear models with short-range interactions. We derive dimension-independent and component-wise error bounds and show the long time path-wise error only has logarithmic dependence on the time range. The theoretical results are verified through some simple numerical tests.},
language = {en}
}
@article{ChangKhalilSchulze2021,
author = {Chang, Der-Chen and Khalil, Sara and Schulze, Bert-Wolfgang},
title = {Analysis on regular corner spaces},
series = {The journal of geometric analysis},
volume = {31},
journal = {The journal of geometric analysis},
number = {9},
publisher = {Springer},
address = {New York},
issn = {1050-6926},
doi = {10.1007/s12220-021-00614-3},
pages = {9199 -- 9240},
year = {2021},
abstract = {We establish a new approach of treating elliptic boundary value problems (BVPs) on manifolds with boundary and regular corners, up to singularity order 2. Ellipticity and parametrices are obtained in terms of symbols taking values in algebras of BVPs on manifolds of corresponding lower singularity orders. Those refer to Boutet de Monvel's calculus of operators with the transmission property, see Boutet de Monvel (Acta Math 126:11-51, 1971) for the case of smooth boundary. On corner configuration operators act in spaces with multiple weights. We mainly study the case of upper left entries in the respective 2 x 2 operator block-matrices of such a calculus. Green operators in the sense of Boutet de Monvel (Acta Math 126:11-51, 1971) analogously appear in singular cases, and they are complemented by contributions of Mellin type. We formulate a result on ellipticity and the Fredholm property in weighted corner spaces, with parametrices of analogous kind.},
language = {en}
}
@unpublished{KytmanovMyslivetsTarkhanov1999,
author = {Kytmanov, Alexander and Myslivets, Simona and Tarkhanov, Nikolai Nikolaevich},
title = {Analytic representation of CR Functions on hypersurfaces with singularities},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25631},
year = {1999},
abstract = {We prove a theorem on analytic representation of integrable CR functions on hypersurfaces with singular points. Moreover, the behaviour of representing analytic functions near singular points is investigated. We are aimed at explaining the new effect caused by the presence of a singularity rather than at treating the problem in full generality.},
language = {en}
}
@unpublished{ElinShoikhetTarkhanov2015,
author = {Elin, Mark and Shoikhet, David and Tarkhanov, Nikolai Nikolaevich},
title = {Analytic semigroups of holomorphic mappings and composition operators},
volume = {4},
number = {6},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-77914},
pages = {30},
year = {2015},
abstract = {In this paper we study the problem of analytic extension in parameter for a semigroup of holomorphic self-mappings of the unit ball in a complex Banach space and its relation to the linear continuous semigroup of composition operators. We also provide a brief review around this topic.},
language = {en}
}
@article{ElinShoikhetTarkhanov2017,
author = {Elin, Mark and Shoikhet, David and Tarkhanov, Nikolai Nikolaevich},
title = {Analytic Semigroups of Holomorphic Mappings and Composition Operators},
series = {Computational Methods and Function Theory},
volume = {18},
journal = {Computational Methods and Function Theory},
number = {2},
publisher = {Springer},
address = {Heidelberg},
issn = {1617-9447},
doi = {10.1007/s40315-017-0227-x},
pages = {269 -- 294},
year = {2017},
abstract = {In this manuscript we provide a review on the classical and resent results related to the problem of analytic extension in parameter for a semigroup of holomorphic self-mappings of the unit ball in a complex Banach space and its relation to the linear continuous semigroup of composition operators.},
language = {en}
}
@unpublished{Tarkhanov2002,
author = {Tarkhanov, Nikolai Nikolaevich},
title = {Anisotropic edge problems},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26280},
year = {2002},
abstract = {We investigate elliptic pseudodifferential operators which degenerate in an anisotropic way on a submanifold of arbitrary codimension. To find Fredholm problems for such operators we adjoint to them boundary and coboundary conditions on the submanifold.The algebra obtained this way is a far reaching generalisation of Boutet de Monvel's algebra of boundary value problems with transmission property. We construct left and right regularisers and prove theorems on hypoellipticity and local solvability.},
language = {en}
}
@unpublished{Paneah2006,
author = {Paneah, Boris},
title = {Another approach to the stability of linear functional operators},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-30139},
year = {2006},
abstract = {Contents: 1 Introduction. 2 The main notations and notions. 3 Statement of results 4 Proofs of the main results.},
language = {en}
}
@phdthesis{Le2006,
author = {Le, Tuan Anh},
title = {Applying realistic mathematics education in Vietnam : teaching middle school geometry},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13480},
school = {Universit{\"a}t Potsdam},
year = {2006},
abstract = {Since 1971, the Freudenthal Institute has developed an approach to mathematics education named Realistic Mathematics Education (RME). The philosophy of RME is based on Hans Freudenthal's concept of 'mathematics as a human activity'. Prof. Hans Freudenthal (1905-1990), a mathematician and educator, believes that 'ready-made mathematics' should not be taught in school. By contrast, he urges that students should be offered 'realistic situations' so that they can rediscover from informal to formal mathematics. Although mathematics education in Vietnam has some achievements, it still encounters several challenges. Recently, the reform of teaching methods has become an urgent task in Vietnam. It appears that Vietnamese mathematics education lacks necessary theoretical frameworks. At first sight, the philosophy of RME is suitable for the orientation of the teaching method reform in Vietnam. However, the potential of RME for mathematics education as well as the ability of applying RME to teaching mathematics is still questionable in Vietnam. The primary aim of this dissertation is to research into abilities of applying RME to teaching and learning mathematics in Vietnam and to answer the question "how could RME enrich Vietnamese mathematics education?". This research will emphasize teaching geometry in Vietnamese middle school. More specifically, the dissertation will implement the following research tasks: • Analyzing the characteristics of Vietnamese mathematics education in the 'reformed' period (from the early 1980s to the early 2000s) and at present; • Implementing a survey of 152 middle school teachers' ideas from several Vietnamese provinces and cities about Vietnamese mathematics education; • Analyzing RME, including Freudenthal's viewpoints for RME and the characteristics of RME; • Discussing how to design RME-based lessons and how to apply these lessons to teaching and learning in Vietnam; • Experimenting RME-based lessons in a Vietnamese middle school; • Analyzing the feedback from the students' worksheets and the teachers' reports, including the potentials of RME-based lessons for Vietnamese middle school and the difficulties the teachers and their students encountered with RME-based lessons; • Discussing proposals for applying RME-based lessons to teaching and learning mathematics in Vietnam, including making suggestions for teachers who will apply these lessons to their teaching and designing courses for in-service teachers and teachers-in training. This research reveals that although teachers and students may encounter some obstacles while teaching and learning with RME-based lesson, RME could become a potential approach for mathematics education and could be effectively applied to teaching and learning mathematics in Vietnamese school.},
language = {en}
}
@phdthesis{Trappmann2007,
author = {Trappmann, Henryk},
title = {Arborescent numbers : higher arithmetic operations and division trees},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-15247},
school = {Universit{\"a}t Potsdam},
year = {2007},
abstract = {The overall program "arborescent numbers" is to similarly perform the constructions from the natural numbers (N) to the positive fractional numbers (Q+) to positive real numbers (R+) beginning with (specific) binary trees instead of natural numbers. N can be regarded as the associative binary trees. The binary trees B and the left-commutative binary trees P allow the hassle-free definition of arbitrary high arithmetic operations (hyper ... hyperpowers). To construct the division trees the algebraic structure "coppice" is introduced which is a group with an addition over which the multiplication is right-distributive. Q+ is the initial associative coppice. The present work accomplishes one step in the program "arborescent numbers". That is the construction of the arborescent equivalent(s) of the positive fractional numbers. These equivalents are the "division binary trees" and the "fractional trees". A representation with decidable word problem for each of them is given. The set of functions f:R1->R1 generated from identity by taking powers is isomorphic to P and can be embedded into a coppice by taking inverses.},
language = {en}
}
@article{Kuzle2018,
author = {Kuzle, Ana},
title = {Assessing metacognition of grade 2 and grade 4 students using an adaptation of multi-method interview approach during mathematics problem-solving},
series = {Mathematics Education Research Journal},
volume = {30},
journal = {Mathematics Education Research Journal},
number = {2},
publisher = {Springer},
address = {Dordrecht},
issn = {1033-2170},
doi = {10.1007/s13394-017-0227-1},
pages = {185 -- 207},
year = {2018},
abstract = {The important role that metacognition plays as a predictor for student mathematical learning and for mathematical problem-solving, has been extensively documented. But only recently has attention turned to primary grades, and more research is needed at this level. The goals of this paper are threefold: (1) to present metacognitive framework during mathematics problem-solving, (2) to describe their multi-method interview approach developed to study student mathematical metacognition, and (3) to empirically evaluate the utility of their model and the adaptation of their approach in the context of grade 2 and grade 4 mathematics problem-solving. The results are discussed not only with regard to further development of the adapted multi-method interview approach, but also with regard to their theoretical and practical implications.},
language = {en}
}
@unpublished{Witt2001,
author = {Witt, Ingo},
title = {Asymptotic algebras},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26069},
year = {2001},
abstract = {The concept of asymptotic type that primarily appears in singular and asymptotic analysis is developed. Especially, asymptotic algebras are introduced.},
language = {en}
}
@unpublished{FangXu2005,
author = {Fang, Daoyuan and Xu, Jiang},
title = {Asymptotic behavior of solutions to multidimensional nonisentropic hydrodynamic model for semiconductors},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29767},
year = {2005},
abstract = {In this paper, a global existence result of smooth solutions to the multidimen- sional nonisentropic hydrodynamic model for semiconductors is proved, under the assumption that the initial data is a perturbation of the stationary solutions for the thermal equilibrium state. The resulting evolutionary solutions converge to the stationary solutions in time asymptotically exponentially fast.},
language = {en}
}
@unpublished{ChenYu2001,
author = {Chen, Hua and Yu, Chun},
title = {Asymptotic behaviour of the trace for Schr{\"o}dinger operator on fractal drums},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26157},
year = {2001},
language = {en}
}
@unpublished{LyTarkhanov2015,
author = {Ly, Ibrahim and Tarkhanov, Nikolai Nikolaevich},
title = {Asymptotic expansions at nonsymmetric cuspidal points},
volume = {4},
number = {7},
publisher = {Universit{\"a}tsverlag Potsdam},
address = {Potsdam},
issn = {2193-6943},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-78199},
pages = {11},
year = {2015},
abstract = {We study asymptotics of solutions to the Dirichlet problem in a domain whose boundary contains a nonsymmetric conical point. We establish a complete asymptotic expansion of solutions near the singular point.},
language = {en}
}