TY - BOOK A1 - Chen, Hua A1 - Wu, Shaohua T1 - On existence of solutions for some hyperbolic-parabolic type chemotaxis systems T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Paneah, Boris T1 - Another approach to the stability of linear functional operators T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - JOUR A1 - Meyerhöfer, Wolfram T1 - Erkennen und Vorurteil : Antwort auf die Replik von Iffert Y1 - 2006 SN - 3- 937786-08-2 ER - TY - BOOK A1 - Gosson, Maurice A. de T1 - Symplectic geometry, wigner-weyl-moyal calculus, and quantum mechanics, in phase space ; Part 1 T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - JOUR A1 - Meyerhöfer, Wolfram A1 - Rienits, Clara T1 - Evaluation des Referendariats im Land Brandenburg, Fachseminare Mathematik Y1 - 2006 SN - 3- 937786-08-2 ER - TY - BOOK A1 - Gosson, Maurice A. de T1 - Symplectic geometry, wigner-weyl-moyal calculus, and quantum mechanics, in phase space ; Part 2 T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Gosson, Maurice A. de T1 - Symplectic geometry, wigner-weyl-moyal calculus, and quantum mechanics, in phase space ; Part 3 T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Kytmanov, Alexander M. A1 - Myslivets, Simona A1 - Tarkhanov, Nikolai Nikolaevich T1 - The bochner-martinelli integral on surfaces with singular points T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK ED - Brückner, Axel T1 - Mathematik : Lehrbuch für die Klasse 7 ; Gymnasium Brandenburg Y1 - 2006 SN - 3-89818-124-3 PB - Paetec CY - Berlin ER - TY - BOOK A1 - Tarkhanov, Nikolai Nikolaevich T1 - Euler characteristic of Fredholm quasicomplexes T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - JOUR A1 - Meyerhöfer, Wolfram T1 - PISA und Co. als kulturindustrielle Phänomene Y1 - 2006 SN - 978-388120-428-6 ER - TY - BOOK A1 - Karp, Lavi T1 - On null quadrature domains T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Krupchyk, K. A1 - Tarkhanov, Nikolai Nikolaevich A1 - Tuomela, J. T1 - Elliptic quasicomplexes in boutet de monvel algebra T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Maergoiz, L. A1 - Tarkhanov, Nikolai Nikolaevich T1 - Optimal recovery from finite set in banach spaces of entire functions T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - THES A1 - Schopka, Sven T1 - Noncommutative Einstein Manifolds Y1 - 2006 CY - Potsdam ER - TY - BOOK A1 - Denk, Robert A1 - Krainer, Thomas T1 - R-Boundedness, pseudodifferential operators and maximal regularity for some classes of partial differential operators T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Brauer, Uwe A1 - Karp, Lavi T1 - Local existence of classical solutions for the Einstin-Euler system using weighted Sobolev spaces of fractional order T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2006 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - THES A1 - Dimitrova, Ilinka T1 - Greenïs equivalences on some classes of transformation semigroups Y1 - 2006 CY - Potsdam ER - TY - JOUR A1 - Blanchard, Gilles A1 - Kawanabe, Motoaki A1 - Sugiyama, Masashi A1 - Spokoiny, Vladimir G. A1 - Müller, Klaus-Robert T1 - In search of non-Gaussian components of a high-dimensional distribution N2 - Finding non-Gaussian components of high-dimensional data is an important preprocessing step for efficient information processing. This article proposes a new linear method to identify the '' non-Gaussian subspace '' within a very general semi-parametric framework. Our proposed method, called NGCA (non-Gaussian component analysis), is based on a linear operator which, to any arbitrary nonlinear (smooth) function, associates a vector belonging to the low dimensional non-Gaussian target subspace, up to an estimation error. By applying this operator to a family of different nonlinear functions, one obtains a family of different vectors lying in a vicinity of the target space. As a final step, the target space itself is estimated by applying PCA to this family of vectors. We show that this procedure is consistent in the sense that the estimaton error tends to zero at a parametric rate, uniformly over the family, Numerical examples demonstrate the usefulness of our method Y1 - 2006 UR - http://portal.acm.org/affiliated/jmlr/ SN - 1532-4435 ER - TY - JOUR A1 - Frank, Jason A1 - Moore, Brian E. A1 - Reich, Sebastian T1 - Linear PDEs and numerical methods that preserve a multisymplectic conservation law N2 - Multisymplectic methods have recently been proposed as a generalization of symplectic ODE methods to the case of Hamiltonian PDEs. Their excellent long time behavior for a variety of Hamiltonian wave equations has been demonstrated in a number of numerical studies. A theoretical investigation and justification of multisymplectic methods is still largely missing. In this paper, we study linear multisymplectic PDEs and their discretization by means of numerical dispersion relations. It is found that multisymplectic methods in the sense of Bridges and Reich [Phys. Lett. A, 284 ( 2001), pp. 184-193] and Reich [J. Comput. Phys., 157 (2000), pp. 473-499], such as Gauss-Legendre Runge-Kutta methods, possess a number of desirable properties such as nonexistence of spurious roots and conservation of the sign of the group velocity. A certain CFL-type restriction on Delta t/Delta x might be required for methods higher than second order in time. It is also demonstrated by means of the explicit midpoint method that multistep methods may exhibit spurious roots in the numerical dispersion relation for any value of Delta t/Delta x despite being multisymplectic in the sense of discrete variational mechanics [J. E. Marsden, G. P. Patrick, and S. Shkoller, Commun. Math. Phys., 199 (1999), pp. 351-395] Y1 - 2006 UR - http://epubs.siam.org/sisc/ U6 - https://doi.org/10.1137/050628271 SN - 1064-8275 ER - TY - JOUR A1 - Dai Pra, Paolo A1 - Louis, Pierre-Yves A1 - Minelli, Ida T1 - Monotonicity and complete monotonicity for continuous-time Markov chains N2 - We analyze the notions of monotonicity and complete monotonicity for Markov Chains in continuous-time, taking values in a finite partially ordered set. Similarly to what happens in discrete-time, the two notions are not equivalent. However, we show that there are partially ordered sets for which monotonicity and complete monotonicity coincide in continuous time but not in discrete-time Y1 - 2006 UR - http://www.elsevier.com/locate/issn/1631073X U6 - https://doi.org/10.1016/j.crma.2006.04.007 SN - 1631-073X ER - TY - INPR A1 - Vasiliev, Serguei A1 - Tarkhanov, Nikolai Nikolaevich T1 - Construction of series of perfect lattices by layer superposition N2 - We construct a new series of perfect lattices in n dimensions by the layer superposition method of Delaunay-Barnes. T3 - Preprints des Instituts für Mathematik der Universität Potsdam - 5 (2016)11 KW - lattice packing and covering KW - polyhedra and polytopes KW - regular figures KW - division of spaces Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-100591 SN - 2193-6943 VL - 5 IS - 11 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Böckmann, Christine A1 - Kirsche, Andreas T1 - Iterative regularization method for lidar remote sensing N2 - In this paper we present an inversion algorithm for ill-posed problems arising in atmospheric remote sensing. The proposed method is an iterative Runge-Kutta type regularization method. Those methods are better well known for solving differential equations. We adapted them for solving inverse ill-posed problems. The numerical performances of the algorithm are studied by means of simulations concerning the retrieval of aerosol particle size distributions from lidar observations. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/00104655 U6 - https://doi.org/10.1016/j.cpc.2005.12.019 SN - 0010-4655 ER - TY - JOUR A1 - Meyerhöfer, Wolfram T1 - Testen, Lernen und Gesellschaft : zwischen Autonomie und Heteronomie Y1 - 2006 SN - 978-388120-428-6 ER - TY - BOOK A1 - Janke, Thomas A1 - Wuttke, Hans A1 - Dietsch, Volker A1 - Janßen, Martin A1 - König, Gerhard A1 - Mentzendorff, Arne A1 - Simanowsky, Ursula A1 - Wuttke, Joachim T1 - Mathematik : Stochastik ; Orientierungswissen Analytische Geometrie ; Gymnasiale Oberstufe, NRW [Schülerbuch] Y1 - 2005 SN - 3-464-57213-7 PB - Cornelsen CY - Berlin ER - TY - JOUR A1 - Schmidt, Hans-Jürgen T1 - Einsteins Arbeiten in Bezug auf die moderne Kosmologie : de Sitters Lösung der Einsteinschen Feldgleichung mit positivem kosmologischen Glied als Geometrie des inflationaeren Weltmodells N2 - Die Arbeit von Albert Einstein von 1918 zu Willem De Sitters Loesung der Einsteinschen Feldgleichung wird unter heutigem Gesichtspunkt kommentiert. Dazu wird zunaechst die Geometrie der De Sitterschen Raum-Zeit beschrieben, sowie ihre Bedeutung fuer das inflationaere Weltmodell erlaeutert. Y1 - 2005 UR - http://arXiv.org/abs/gr-qc/0506121 ER - TY - BOOK A1 - Janke, Thomas A1 - Wuttke, Hans A1 - Dietsch, Volker A1 - Janßen, Martin A1 - Koenig, Gerhard A1 - Mentzendorff, Arne A1 - Simanowsky, Ursula A1 - Wuttke, Joachim ED - Jahnke, Thomas T1 - Mathematik : Stochastik ; Gymnasiale Oberstufe, [Schülerbuch] Y1 - 2005 SN - 3-464-57218-8 PB - Cornelsen CY - Berlin ER - TY - JOUR A1 - Pfäffle, Frank T1 - Eigenvalues of Dirac Operators for Hyperbolic Degenerations N2 - We study the behaviour of the spectrum of the Dirac operator for sequences of compact hyperbolic manifolds whose limit is non-compact. If the spectrum of the limit manifold is descrete we show that the spectrum is approximated by the spectra of compact manifolds. Y1 - 2005 UR - http://www.springerlink.com/app/home/ contribution.asp?wasp=74877684beab42c4a04190542f838968&referrer=parent&backto=issue,1,6;journal,6,89;searchpublicationsre sults,1,2; ER - TY - BOOK A1 - Janke, Thomas A1 - Wuttke, Hans A1 - Dietsch, Volker A1 - Janßen, Martin A1 - König, Gerhard A1 - Mentzendorff, Arne A1 - Simanowsky, Ursula A1 - Wuttke, Joachim T1 - Mathematik : Stochastik ; Handreichungen für den Unterricht ; Gymnasiale Oberstufe [Schülerbuch] Y1 - 2005 SN - 3-464-57288-9 PB - Cornelsen CY - Berlin ER - TY - BOOK A1 - Tarkhanov, Nikolai Nikolaevich T1 - Unitary solutions of paratial differential equations T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2005 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Liu, Weian T1 - Monotone method for nonlocal systems of first order T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2005 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - JOUR A1 - Zähle, Henryk T1 - Space-time regularity of catalytic super-Brownian motion N2 - The paper studies catalytic super-Brownian motion on the real line, where the branching rate is controlled by a catalyst. D. A. Dawson, K. Fleischmann and S. Roelly showed, for a broad class of catalysts, that, as for constant branching, the processes are absolutely continuous measures. This paper considers a class of catalysts, called moderate, which must satisfy a uniform boundedness condition and a condition controlling the degree of singularity---essentially that the mass of catalyst in small balls should (uniformly) be of order r^a, where a>0. The main result of this paper shows that for this class of catalysts there is a continuous density field for the process. Moreover the density is the unique solution (in law) of an appropriate SPDE. Y1 - 2005 UR - http://www.interscience.wiley.com/jpages/0025-584X/ ER - TY - THES A1 - Rätsch, Thoralf T1 - On the Equi-Constistency of the failure of the GAP-1 transfer property and an inaccessible cardinal Y1 - 2005 CY - Potsdam ER - TY - BOOK ED - Brückner, Axel T1 - Mathematik : Lehrbuch für die Klasse 10 ; Gymnasium Brandenburg Y1 - 2005 SN - 3-89818-142-1 PB - Paetec CY - Berlin ER - TY - BOOK A1 - Paneah, Boris T1 - On the general theory of the cauchy type functional equations with applications in analysis T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2005 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - JOUR A1 - Böckmann, Christine A1 - Mironova, I. A1 - Muller, D. T1 - Microphysical aerosol parameters from multiwavelength lidar N2 - The hybrid regularization technique developed at the Institute of Mathematics of Potsdam University (IMP) is used to derive microphysical properties such as effective radius, surface-area concentration, and volume concentration, as well as the single-scattering albedo and a mean complex refractive index, from multiwavelength lidar measurements. We present the continuation of investigations of the IMP method. Theoretical studies of the degree of ill-posedness of the underlying model, simulation results with respect to the analysis of the retrieval error of microphysical particle properties from multiwavelength lidar data, and a comparison of results for different numbers of backscatter and extinction coefficients are presented. Our analysis shows that the backscatter operator has a smaller degree of ill- posedness than the operator for extinction. This fact underlines the importance of backscatter data. Moreover, the degree of ill-posedness increases with increasing particle absorption, i.e., depends on the imaginary part of the refractive index and does not depend significantly on the real part. Furthermore, an extensive simulation study was carried out for logarithmic-normal size distributions with different median radii, mode widths, and real and imaginary parts of refractive indices. The errors of the retrieved particle properties obtained from the inversion of three backscatter (355, 532, and 1064 nm) and two extinction (355 and 532 nm) coefficients were compared with the uncertainties for the case of six backscatter (400. 710, 800 nm. additionally) and the same two extinction coefficients. For known complex refractive index and up to 20% normally distributed noise, we found that the retrieval errors for effective radius, surface-area concentration, and volume concentration stay below approximately 15% in both cases. Simulations were also made with unknown complex refractive index. In that case the integrated parameters stay below approximately 30%, and the imaginary part of the refractive index stays below 35% for input noise up to 10% in both cases. In general, the quality of the retrieved aerosol parameters depends strongly on the imaginary part owing to the degree of ill-posedness. It is shown that under certain constraints a minimum data set of three backscatter coefficients and two extinction coefficients is sufficient for a successful inversion. The IMP algorithm was finally tested for a measurement case. (C) 2005 Optical Society of America Y1 - 2005 SN - 1084-7529 ER - TY - JOUR A1 - Bovier, Anton A1 - Gayrard, Veronique A1 - Klein, Markus T1 - Metastability in reversible diffusion processes : II. Precise asymptotics for small eigenvalues N2 - We continue the analysis of the problem of metastability for reversible diffusion processes, initiated in [BEGK3], with a precise analysis of the low-lying spectrum of the generator. Recall that we are considering processes with generators of the form -epsilonDelta + delF(.) del on R-d or subsets of Rd, where F is a smooth function with finitely many local minima. Here we consider only the generic situation where the depths of all local minima are different. We show that in general the exponentially small part of the spectrum is given, up to multiplicative errors tending to one, by the eigenvalues of the classical capacity matrix of the array of capacitors made of balls of radius epsilon centered at the positions of the local minima of F. We also get very precise uniform control on the corresponding eigenfunctions. Moreover, these eigenvalues can be identified with the same precision with the inverse mean metastable exit times from each minimum. In [BEGK3] it was proven that these mean times are given, again up to multiplicative errors that tend to one, by the classical Eyring- Kramers formula Y1 - 2005 SN - 1435-9855 ER - TY - JOUR A1 - Rasch, T. A1 - Schindler, R. T1 - A new condensation principle N2 - We generalize del(A), which was introduced in [Schinfinity], to larger cardinals. For a regular cardinal kappa>N-0 we denote by del(kappa)(A) the statement that Asubset of or equal tokappa and for all regular theta>kappa(o), {X is an element of[L-theta[A]](<) : X &AND; &ISIN; &AND; otp (X &AND; Ord) &ISIN; Card (L[A&AND;X&AND;])} is stationary in [L-[A]](<). It was shown in [Sch&INFIN;] that &DEL;(N1) (A) can hold in a set-generic extension of L. We here prove that &DEL;(N2) (A) can hold in a set-generic extension of L as well. In both cases we in fact get equiconsistency theorems. This strengthens results of [Ra00] and [Ran01]. &DEL;(N3) () is equivalent with the existence of 0# Y1 - 2005 SN - 1432-0665 ER - TY - JOUR A1 - Gosson, Maurice A. de T1 - Extended Weyl calculus and application to the phase-space Schrodinger equation N2 - We show that the Schrodinger equation in phase space proposed by Torres-Vega and Frederick is canonical in the sense that it is a natural consequence of the extended Weyl calculus obtained by letting the Heisenberg group act on functions (or half-densities) defined on phase space. This allows us, in passing, to solve rigorously the TF equation for all quadratic Hamiltonians Y1 - 2005 ER - TY - JOUR A1 - Baumgaertel, Hellmut A1 - Grundling, H. T1 - Superselection in the presence of constraints N2 - Superselection and constraints occur together in many gauge theories, and here we begin a study of such systems. Our main focus will be to analyze compatibility questions between constraining and superselection, and we will develop an example modelled on QED in which our framework is realized. We proceed from a generalization of Doplicher- Roberts superselection theory to the case of the nontrivial center, and a set of Dirac quantum constraints and find conditions under which the superselection structures will survive constraining in some form. This involves an analysis of the restriction and factorization of superselection structures. (c) 2005 American Institute of Physics Y1 - 2005 SN - 0022-2488 ER - TY - JOUR A1 - Baake, Ellen A1 - Baake, Michael A1 - Bovier, Anton A1 - Klein, Markus T1 - An asymptotic maximum principle for essentially linear evolution models N2 - Recent work on mutation-selection models has revealed that, under specific assumptions on the fitness function and the mutation rates, asymptotic estimates for the leading eigenvalue of the mutation-reproduction matrix may be obtained through a low-dimensional maximum principle in the limit N --> infinity (where N, or N-d with d greater than or equal to 1, is proportional to the number of types). In order to extend this variational principle to a larger class of models, we consider here a family of reversible matrices of asymptotic dimension N-d and identify conditions under which the high-dimensional Rayleigh-Ritz variational problem may be reduced to a low-dimensional one that yields the leading eigenvalue up to an error term of order 1/N. For a large class of mutation-selection models, this implies estimates for the mean fitness, as well as a concentration result for the ancestral distribution of types Y1 - 2005 SN - 0303-6812 ER - TY - JOUR A1 - Klein, Markus A1 - Korotyaev, Evgeni A1 - Pokrovski, A. T1 - Spectral asymptotics of the harmonic oscillator perturbed by bounded potentials N2 - Consider the operator T = -d(2)/dx(2) + x(2) + q(x) in L-2 (R), where q is a real function with q' and integral(0)(x) q(s) ds bounded. The spectrum of T is purely discrete and consists of simple eigenvalues. We determine their asymptotics mu(n) = (2n + 1) + (2 pi)(-1) integral(-pi)(pi) q(root 2n+1 sin theta)d theta + O(n(-1/3)) and we extend these results for complex q. Y1 - 2005 SN - 1424-0637 ER - TY - JOUR A1 - Gunther, U. A1 - Zhuk, Alexandre A1 - Bezerra, Valdir B. A1 - Romero, C. T1 - AdS and stabilized extra dimensions in multi-dimensional gravitational models with nonlinear scalar curvature terms R-1 and R-4 N2 - We study multi-dimensional gravitational models with scalar curvature nonlinearities of types R-1 and R-4. It is assumed that the corresponding higher dimensional spacetime manifolds undergo a spontaneous compactification to manifolds with a warped product structure. Special attention has been paid to the stability of the extra-dimensional factor spaces. It is shown that for certain parameter regions the systems allow for a freezing stabilization of these spaces. In particular, we find for the R-1 model that configurations with stabilized extra dimensions do not provide a late-time Acceleration (they are AdS), whereas the solution branch which allows. for accelerated expansion (the dS branch) is incompatible with stabilized factor spaces. In the case of the R-4 model, we obtain that the stability region in parameter space depends on the total dimension D = dim(M) of the higher dimensional spacetime M. Tor D > 8 the stability region consists of a single (absolutely stable) sector which is shielded from a conformal singularity (and an antigravity sector beyond it) by a potential barrier of infinite height and width. This sector is smoothly connected with the stability region of a curvature-linear model. For D < 8 an additional (metastable) sector exists Which is separated from the conformal singularity by a potential barrier of finite height and width so that systems in this sector are prone to collapse into the conformal singularity. This second sector is not smoothly connected with the first (absolutely stable) one. Several limiting cases and the possibility of inflation are discussed for the R-4 model Y1 - 2005 SN - 0264-9381 ER - TY - JOUR A1 - Holschneider, Matthias A1 - Diallo, Mamadou Sanou A1 - Kulesh, Michail A1 - Ohrnberger, Matthias A1 - Luck, E. A1 - Scherbaum, Frank T1 - Characterization of dispersive surface waves using continuous wavelet transforms N2 - In this paper, we propose a method of surface waves characterization based on the deformation of the wavelet transform of the analysed signal. An estimate of the phase velocity (the group velocity) and the attenuation coefficient is carried out using a model-based approach to determine the propagation operator in the wavelet domain, which depends nonlinearly on a set of unknown parameters. These parameters explicitly define the phase velocity, the group velocity and the attenuation. Under the assumption that the difference between waveforms observed at a couple of stations is solely due to the dispersion characteristics and the intrinsic attenuation of the medium, we then seek to find the set of unknown parameters of this model. Finding the model parameters turns out to be that of an optimization problem, which is solved through the minimization of an appropriately defined cost function. We show that, unlike time-frequency methods that exploit only the square modulus of the transform, we can achieve a complete characterization of surface waves in a dispersive and attenuating medium. Using both synthetic examples and experimental data, we also show that it is in principle possible to separate different modes in both the time domain and the frequency domain Y1 - 2005 SN - 0956-540X ER - TY - JOUR A1 - Savin, Anton A1 - Sternin, Boris T1 - Boundary value problems on manifolds with fibered boundary N2 - We define a class of boundary value problems on manifolds with fibered boundary. This class is in a certain sense a deformation between the classical boundary value problems and the Atiyah-Patodi-Singer problems in subspaces (it contains both as special cases). The boundary conditions in this theory are taken as elements of the C*-algebra generated by pseudodifferential operators and families of pseudodifferential operators in the fibers. We prove the Fredholm. property for elliptic boundary value problems and compute a topological obstruction (similar to Atiyah-Bott obstruction) to the existence of elliptic boundary conditions for a given elliptic operator. Geometric operators with trivial and nontrivial obstruction are given. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Y1 - 2005 SN - 0025-584X ER - TY - JOUR A1 - Shlapunov, Alexander A1 - Tarkhanov, Nikolai Nikolaevich T1 - Mixed problems with parameter N2 - Let X be a smooth n-dimensional manifold and D be an open connected set in X with smooth boundary OD. Perturbing the Cauchy problem for an elliptic system Au = f in D with data on a closed set Gamma subset of partial derivativeD, we obtain a family of mixed problems depending on a small parameter epsilon > 0. Although the mixed problems are subjected to a noncoercive boundary condition on partial derivativeDF in general, each of them is uniquely solvable in an appropriate Hilbert space D-T and the corresponding family {u(epsilon)} of solutions approximates the solution of the Cauchy problem in D-T whenever the solution exists. We also prove that the existence of a solution to the Cauchy problem in D-T is equivalent to the boundedness of the family {u(epsilon)}. We thus derive a solvability condition for the Cauchy problem and an effective method of constructing the solution. Examples for Dirac operators in the Euclidean space R-n are treated. In this case, we obtain a family of mixed boundary problems for the Helmholtz equation Y1 - 2005 SN - 1061-9208 ER - TY - JOUR A1 - Savin, Anton T1 - Elliptic operators on manifolds with singularities and K-homology N2 - Elliptic operators on smooth compact manifolds are classified by K-homology. We prove that a similar classification is valid also for manifolds with simplest singularities: isolated conical points and edges. The main ingredients of the proof of these results are: Atiyah-Singer difference construction in the noncommutative case and Poincare isomorphism in K- theory for ( our) singular manifolds. As an application we give a formula in topological terms for the obstruction to Fredholm problems on manifolds with edges Y1 - 2005 SN - 0920-3036 ER - TY - BOOK A1 - Berman, Gennady A1 - Tarkhanov, Nikolai Nikolaevich T1 - The dynamics of four wave interactions T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2004 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Shlapunov, Alexander A1 - Tarkhanov, Nikolai Nikolaevich T1 - Mixed problems with a parameter T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2004 SN - 1437-739X PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Popivanov, P. R. T1 - Lorenz transformations and creation of logarithmic singularities to the solutions of some nonstrictly hyperbolic semilinear systems with two space variables T3 - Preprint / Universität Potsdam, Institut für Mathematik, Arbeitsgruppe Partiell Y1 - 2004 SN - 1437-739X PB - Univ. CY - Potsdam ER -