TY - JOUR A1 - Anger, Christian A1 - Gebser, Martin A1 - Janhunen, Tomi A1 - Schaub, Torsten H. T1 - What's a head without a body? Y1 - 2006 ER - TY - JOUR A1 - Gerbser, Martin A1 - Lee, Joohyung A1 - Lierler, Yuliya T1 - Elementary sets for logic programs Y1 - 2006 SN - 978-1-57735-281-5 ER - TY - JOUR A1 - Gerbser, Martin A1 - Schaub, Torsten H. T1 - Characterizing (ASP) inferences by unit propagation Y1 - 2006 ER - TY - JOUR A1 - Konczak, Kathrin T1 - Weak order equivalence for Logic Programs with Prefernces Y1 - 2006 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - A preference-based framework for updating logic programs Y1 - 2007 SN - 978-3-540- 72199-4 ER - TY - JOUR A1 - Mileo, Alessandra A1 - Schaub, Torsten H. T1 - Qualitative constraint enforcement in advanced policy specification Y1 - 2007 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Lang, Jérôme A1 - Schaub, Torsten H. T1 - Belief change based on global minimisation Y1 - 2007 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Graphs and colorings for answer set programming N2 - We investigate the usage of rule dependency graphs and their colorings for characterizing and computing answer sets of logic programs. This approach provides us with insights into the interplay between rules when inducing answer sets. We start with different characterizations of answer sets in terms of totally colored dependency graphs that differ ill graph-theoretical aspects. We then develop a series of operational characterizations of answer sets in terms of operators on partial colorings. In analogy to the notion of a derivation in proof theory, our operational characterizations are expressed as (non-deterministically formed) sequences of colorings, turning an uncolored graph into a totally colored one. In this way, we obtain an operational framework in which different combinations of operators result in different formal properties. Among others, we identify the basic strategy employed by the noMoRe system and justify its algorithmic approach. Furthermore, we distinguish operations corresponding to Fitting's operator as well as to well-founded semantics Y1 - 2006 UR - http://www.cs.kuleuven.ac.be/~dtai/projects/ALP//TPLP/ U6 - https://doi.org/10.1017/S1471068405002528 SN - 1471-0684 ER - TY - JOUR A1 - Gebser, Martin A1 - Schaub, Torsten H. A1 - Thiele, Sven T1 - GrinGo : a new grounder for answer set programming Y1 - 2007 SN - 978-3-540- 72199-4 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Vogel, Ralf T1 - Abduction and Preferences in Linguistics Y1 - 2005 UR - http://www.cs.uni-potsdam.de/~konczak/Papers/konvog05a.pdf ER - TY - JOUR A1 - Calude, C. S. A1 - Jurgensen, Helmut T1 - Is complexity a source of incompleteness? N2 - In this paper we prove Chaitin's "heuristic principle," the theorems of a finitely-specified theory cannot be significantly more complex than the theory itself, for an appropriate measure of complexity. We show that the measure is invariant under the change of the Godel numbering. For this measure, the theorems of a finitely-specified, sound, consistent theory strong enough to formalize arithmetic which is arithmetically sound (like Zermelo-Fraenkel set theory with choice or Peano Arithmetic) have bounded complexity, hence every sentence of the theory which is significantly more complex than the theory is unprovable. Previous results showing that incompleteness is not accidental, but ubiquitous are here reinforced in probabilistic terms: the probability that a true sentence of length n is provable in the theory tends to zero when n tends to infinity, while the probability that a sentence of length n is true is strictly positive. (c) 2004 Elsevier Inc. All rights reserved Y1 - 2005 SN - 0196-8858 ER - TY - JOUR A1 - Bordihn, Henning T1 - On the number of components in cooperating distributed grammar systems N2 - It is proved that the number of components in context-free cooperating distributed (CD) grammar systems can be reduced to 3 when they are working in the so-called sf-mode of derivation, which is the cooperation protocol which has been considered first for CD grammar systems. In this derivation mode, a component continues the derivation until and unless there is a nonterminal in the sentential form which cannot be rewritten according to that component. Moreover, it is shown that CD grammar systems in sf-mode with only one component can generate only the context-free languages but they can generate non-context-free languages if two components are used. The sf-mode of derivation is compared with other well-known cooperation protocols with respect to the hierarchies induced by the number of components. (C) 2004 Elsevier B.V. All rights reserved Y1 - 2005 SN - 0304-3975 ER - TY - JOUR A1 - Beerenwinkel, Niko A1 - Sing, Tobias A1 - Lengauer, Thomas A1 - Rahnenfuhrer, Joerg A1 - Roomp, Kirsten A1 - Savenkov, Igor A1 - Fischer, Roman A1 - Hoffmann, Daniel A1 - Selbig, Joachim A1 - Korn, Klaus A1 - Walter, Hauke A1 - Berg, Thomas A1 - Braun, Patrick A1 - Faetkenheuer, Gerd A1 - Oette, Mark A1 - Rockstroh, Juergen A1 - Kupfer, Bernd A1 - Kaiser, Rolf A1 - Daeumer, Martin T1 - Computational methods for the design of effective therapies against drug resistant HIV strains N2 - The development of drug resistance is a major obstacle to successful treatment of HIV infection. The extraordinary replication dynamics of HIV facilitates its escape from selective pressure exerted by the human immune system and by combination drug therapy. We have developed several computational methods whose combined use can support the design of optimal antiretroviral therapies based on viral genomic data Y1 - 2005 ER - TY - JOUR A1 - Brzozowski, J. A. A1 - Jürgensen, Helmut T1 - Representation of semiautomata by canonical words and equivalences N2 - We study a novel representation of semiautomata, which is motivated by the method of trace-assertion specifications of software modules. Each state of the semiautomaton is represented by an arbitrary word leading to that state, the canonical word. The transitions of the semiautomaton give rise to a right congruence, the state-equivalence, on the set of input words of the semiautomaton: two words are state-equivalent if and only if they lead to the same state. We present a simple algorithm for finding a set of generators for state-equivalence. Directly from this set of generators, we construct a confluent prefix-rewriting system which permits us to transform any word to its canonical representative. In general, the rewriting system may allow infinite derivations. To address this issue, we impose the condition of prefix-continuity on the set of canonical words. A set is prefix-continuous if, whenever a word w and a prefix u of w axe in the set, then all the prefixes of w longer than u are also in the set. Prefix-continuous sets include prefix-free and prefix-closed sets as special cases. We prove that the rewriting system is Noetherian if and only if the set of canonical words is prefix-continuous. Furthermore, if the set of canonical words is prefix- continuous, then the set of rewriting rules is irredundant. We show that each prefix-continuous canonical set corresponds to a spanning forest of the semiautomaton Y1 - 2005 SN - 0129-0541 ER - TY - JOUR A1 - Bordihn, Henning A1 - Holzer, Markus A1 - Kutrib, Martin T1 - Unsolvability levels of operation problems for subclasses of context-free languages N2 - We investigate the operation problem for linear and deterministic context-free languages: Fix an operation on formal languages. Given linear (deterministic, respectively) context-free languages, is the application of this operation to the given languages still a linear (deterministic, respectively) context-free language? Besides the classical operations, for which the linear and deterministic context-free languages are not closed, we also consider the recently introduced root and power operation. We show non-semidecidability, to be more precise, we show completeness for the second level of the arithmetic hierarchy for all of the aforementioned operations, except for the power operation, if the underlying alphabet contains at least two letters. The result for the power opera, tion solves an open problem stated in Theoret. Comput. Sci. 314 (2004) 445-449 Y1 - 2005 SN - 0129-0541 ER - TY - JOUR A1 - Bruggemeier, M. A1 - Dovifat, A. A1 - Kubisch, D. T1 - Micropolitical innovation arenas as a tool for analyzing innovation processes in the context of electronic government N2 - E-Government requires technical and organizational innovation. Research has already shown that the respective innovation process is complex and contingent upon specific organizational structures. Managing such innovation processes successfully is difficult. Drawing on assumptions of micropolitical behavior, a framework of innovation arenas is proposed. It supports the analysis of ongoing E-Government projects as well as the ex post investigation of successful or failed projects. Testing this framework in case studies already demonstrates its usefulness for individual actors making strategic choices about change management. Furthermore, the results indicate that many commonly held assumptions about successful change management have to be reconsidered Y1 - 2005 SN - 0937-6429 ER - TY - JOUR A1 - Meinecke, Frank C. A1 - Ziehe, Andreas A1 - Kurths, Jürgen A1 - Müller, Klaus-Robert T1 - Measuring phase synchronization of superimposed signals N2 - Phase synchronization is an important phenomenon that occurs in a wide variety of complex oscillatory processes. Measuring phase synchronization can therefore help to gain fundamental insight into nature. In this Letter we point out that synchronization analysis techniques can detect spurious synchronization, if they are fed with a superposition of signals such as in electroencephalography or magnetoencephalography data. We show how techniques from blind source separation can help to nevertheless measure the true synchronization and avoid such pitfalls Y1 - 2005 SN - 0031-9007 ER - TY - JOUR A1 - Scholz, Matthias A1 - Kaplan, F. A1 - Guy, C. L. A1 - Kopka, Joachim A1 - Selbig, Joachim T1 - Non-linear PCA : a missing data approach N2 - Motivation: Visualizing and analysing the potential non-linear structure of a dataset is becoming an important task in molecular biology. This is even more challenging when the data have missing values. Results: Here, we propose an inverse model that performs non-linear principal component analysis (NLPCA) from incomplete datasets. Missing values are ignored while optimizing the model, but can be estimated afterwards. Results are shown for both artificial and experimental datasets. In contrast to linear methods, non-linear methods were able to give better missing value estimations for non-linear structured data. Application: We applied this technique to a time course of metabolite data from a cold stress experiment on the model plant Arabidopsis thaliana, and could approximate the mapping function from any time point to the metabolite responses. Thus, the inverse NLPCA provides greatly improved information for better understanding the complex response to cold stress Y1 - 2005 SN - 1367-4803 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Graphs and cologings for answer set programming : adridged report Y1 - 2004 SN - 3-540- 20721-x ER - TY - JOUR A1 - Boesel, Andreas A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Profiling answer set programming : the visualization component of the noMoRe System Y1 - 2004 SN - 3-540-23242-7 ER - TY - JOUR A1 - Cordes, Frank A1 - Kaiser, Rolf A1 - Selbig, Joachim T1 - Bioinformatics approach to predicting HIV drug resistance N2 - The emergence of drug resistance remains one of the most challenging issues in the treatment of HIV-1 infection. The extreme replication dynamics of HIV facilitates its escape from the selective pressure exerted by the human immune system and by the applied combination drug therapy. This article reviews computational methods whose combined use can support the design of optimal antiretroviral therapies based on viral genotypic and phenotypic data. Genotypic assays are based on the analysis of mutations associated with reduced drug susceptibility, but are difficult to interpret due to the numerous mutations and mutational patterns that confer drug resistance. Phenotypic resistance or susceptibility can be experimentally evaluated by measuring the inhibition of the viral replication in cell culture assays. However, this procedure is expensive and time consuming Y1 - 2006 UR - http://www.expert-reviews.com/loi/erm U6 - https://doi.org/10.1586/14737159.6.2.207 SN - 1473-7159 ER - TY - JOUR A1 - Lemm, Steven A1 - Curio, Gabriel A1 - Hlushchuk, Yevhen A1 - Müller, Klaus-Robert T1 - Enhancing the signal-to-noise ratio of ICA-based extracted ERPs N2 - When decomposing single trial electroencephalography it is a challenge to incorporate prior physiological knowledge. Here, we develop a method that uses prior information about the phase-locking property of event-related potentials in a regularization framework to bias a blind source separation algorithm toward an improved separation of single-trial phase-locked responses in terms of an increased signal-to-noise ratio. In particular, we suggest a transformation of the data, using weighted average of the single trial and trial-averaged response, that redirects the focus of source separation methods onto the subspace of event-related potentials. The practical benefit with respect to an improved separation of such components from ongoing background activity and extraneous noise is first illustrated on artificial data and finally verified in a real-world application of extracting single-trial somatosensory evoked potentials from multichannel EEG-recordings Y1 - 2006 UR - http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=10 U6 - https://doi.org/10.1109/Tbme.2006.870258 SN - 0018-9294 ER - TY - JOUR A1 - Gressmann, Jean A1 - Janhunen, Tomi A1 - Mercer, Robert E. A1 - Schaub, Torsten H. A1 - Thiele, Sven A1 - Tichy, Richard T1 - On probing and multi-threading in platypus Y1 - 2006 ER - TY - JOUR A1 - Laub, Julian A1 - Roth, Volker A1 - Buhmann, Joachim A1 - Müller, Klaus-Robert T1 - On the information and representation of non-Euclidean pairwise data N2 - Two common data representations are mostly used in intelligent data analysis, namely the vectorial and the pairwise representation. Pairwise data which satisfy the restrictive conditions of Euclidean spaces can be faithfully translated into a Euclidean vectorial representation by embedding. Non-metric pairwise data with violations of symmetry, reflexivity or triangle inequality pose a substantial conceptual problem for pattern recognition since the amount of predictive structural information beyond what can be measured by embeddings is unclear. We show by systematic modeling of non-Euclidean pairwise data that there exists metric violations which can carry valuable problem specific information. Furthermore, Euclidean and non-metric data can be unified on the level of structural information contained in the data. Stable component analysis selects linear subspaces which are particularly insensitive to data fluctuations. Experimental results from different domains support our pattern recognition strategy. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/00313203 U6 - https://doi.org/10.1016/j.patcog.2006.04.016 SN - 0031-3203 ER - TY - JOUR A1 - Mileo, Alessandra A1 - Schaub, Torsten H. T1 - Extending ordered disjunctions for policy enforcement : preliminary report Y1 - 2006 UR - http://www.easychair.org/FLoC-06/PREFS-preproceedings.pdf ER - TY - JOUR A1 - Kawanabe, Motoaki A1 - Blanchard, Gilles A1 - Sugiyama, Masashi A1 - Spokoiny, Vladimir G. A1 - Müller, Klaus-Robert T1 - A novel dimension reduction procedure for searching non-Gaussian subspaces N2 - In this article, we consider high-dimensional data which contains a low-dimensional non-Gaussian structure contaminated with Gaussian noise and propose a new linear method to identify the non-Gaussian subspace. Our method NGCA (Non-Gaussian Component Analysis) is based on a very general semi-parametric framework and has a theoretical guarantee that the estimation error of finding the non-Gaussian components tends to zero at a parametric rate. NGCA can be used not only as preprocessing for ICA, but also for extracting and visualizing more general structures like clusters. A numerical study demonstrates the usefulness of our method Y1 - 2006 UR - http://www.springerlink.com/content/105633/ U6 - https://doi.org/10.1007/11679363_19 SN - 0302-9743 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Liu, Daphne H. A1 - Schaub, Torsten H. A1 - Thiele, Sven T1 - COBA 2.0 : a consistency-based belief change system Y1 - 2006 UR - http://www2.in.tu-clausthal.de/~tmbehrens/NMR_Proc_TR4.pdf ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - An Extended Query language for action languages (and its application to aggregates and preferences) Y1 - 2006 UR - http://www2.in.tu-clausthal.de/~tmbehrens/NMR_Proc_TR4.pdf ER - TY - JOUR A1 - Pernici, Barbara A1 - Weske, Mathias T1 - Business process management Y1 - 2006 SN - 0169-023X ER - TY - JOUR A1 - Camales, Renaud T1 - Explicit formulation of the solution of Hamada-Leray-Wagschal's theorem N2 - In this paper, an explicit formula of the solution of Hainada-Leray-Wagschal's theorem is given. For this, only structure's theorem of finite dimensional determination's function and linear algebra technics developped in [1] are used Y1 - 2005 SN - 0034-5318 ER - TY - JOUR A1 - Häger, Sebastian A1 - Schubert, Wolfgang T1 - Assoziationen in Softwarearchitekturen JF - Preprint / Universität Potsdam, Institut für Informatik Y1 - 2005 SN - 0946-7580 VL - 2005, 2 PB - Univ. CY - Potsdam ER - TY - JOUR A1 - Anger, Christian A1 - Gebser, Martin A1 - Linke, Thomas A1 - Neumann, Andre A1 - Schaub, Torsten H. T1 - The nomore++ approach to answer set solving Y1 - 2005 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/angelinesc05c.pdf ER - TY - JOUR A1 - Gressmann, Jean A1 - Janhunen, Tomi A1 - Mercer, Robert E. A1 - Schaub, Torsten H. A1 - Thiele, Sven A1 - Tichy, Richard T1 - Platypus : a platform for distributed answer set solving Y1 - 2005 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/grjamescthti05a.pdf ER - TY - JOUR A1 - Anger, Christian A1 - Gebser, Martin A1 - Linke, Thomas A1 - Neumann, Andre A1 - Schaub, Torsten H. T1 - The nomore++ approach to answer set solving Y1 - 2005 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/angelinesc05c.pdf ER - TY - JOUR A1 - Grell, Susanne A1 - Konczak, Kathrin A1 - Schaub, Torsten H. T1 - nomore) : a system for computing preferred Answer Sets Y1 - 2005 SN - 0302-9743 ER - TY - JOUR A1 - Faber, Wolfgang A1 - Konczak, Kathrin T1 - Strong Equivalence for Logic Programs with Preferences Y1 - 2005 UR - http://www.cs.uni-potsdam.de/~konczak/Papers/fabkon05a.pdf ER - TY - JOUR A1 - Anger, Christian A1 - Konczak, Kathrin A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - A Glimpse of Answer Set Programming Y1 - 2005 UR - http://www.cs.uni-potsdam.de/~konczak/Papers/ankolisc05.pdf SN - 0170-4516 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Lang, Jerome T1 - Voting procedures with incomplete preferences Y1 - 2005 UR - http://koala.ilog.fr/wiki/pub/Preference05/WsProceedings/Pref05.pdf ER - TY - JOUR A1 - Konczak, Kathrin A1 - Vogel, Ralf T1 - Abduction and preferences in linguistics : Extended abstract Y1 - 2005 UR - http://www.cs.uni-potsdam.de/~konczak/Papers/konvog05b.pdf SN - 0302-9743 ER - TY - JOUR A1 - Goessel, Michael A1 - Morozov, A. V. A1 - Sapozhnikov, V. V. A1 - Sapozhaikov, Vl. V. T1 - Checking combinational circuits by the method of logic complement N2 - Design of fully self-testing combinational circuits was considered. A theorem defining the conditions for guaranteed logic complement-based design of fully self-testing circuit was proved. Examples were presented Y1 - 2005 SN - 0005-1179 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Expressing default logic variants in default logic N2 - Reiter's default logic is one of the best known and most studied of the approaches to nonmonotonic reasoning. Several variants of default logic have subsequently been proposed to give systems with properties differing from the original. In this paper, we examine the relationship between default logic and its major variants. We accomplish this by translating a default theory under a variant interpretation into a second default theory, under the original Reiter semantics, wherein the variant interpretation is respected. That is, in each case we show that, given an extension of a translated theory, one may extract an extension of the original variant default logic theory. We show how constrained, rational, justified, and cumulative default logic can be expressed in Reiter's default logic. As well, we show how Reiter's default logic can be expressed in rational default logic. From this, we suggest that any such variant can be similarly treated. Consequently, we provide a unification of default logics, showing how the original formulation of default logic may express its variants. Moreover, the translations clearly express the relationships between alternative approaches to default logic. The translations themselves are shown to generally have good properties. Thus, in at least a theoretical sense, we show that these variants are in a sense superfluous, in that for any of these variants of default logic, we can exactly mimic the behaviour of a variant in standard default logic. As well, the translations lend insight into means of classifying the expressive power of default logic variants; specifically we suggest that the property of semi-monotonicity represents a division with respect to expressibility, whereas regularity and cumulativity do not Y1 - 2005 SN - 0955-792X ER - TY - JOUR A1 - Gebser, Martin A1 - Liu, Lengning A1 - Namasivayam, Gayathri A1 - Neumann, André A1 - Schaub, Torsten H. A1 - Truszczynski, Miroslaw T1 - The first answer set programming system competition Y1 - 2007 SN - 978-3-540- 72199-4 ER - TY - JOUR A1 - Meinecke, Frank C. A1 - Harmeling, Stefan A1 - Müller, Klaus-Robert T1 - Inlier-based ICA with an application to superimposed images N2 - This paper proposes a new independent component analysis (ICA) method which is able to unmix overcomplete mixtures of sparce or structured signals like speech, music or images. Furthermore, the method is designed to be robust against outliers, which is a favorable feature for ICA algorithms since most of them are extremely sensitive to outliers. Our approach is based on a simple outlier index. However, instead of robustifying an existing algorithm by some outlier rejection technique we show how this index can be used directly to solve the ICA problem for super-Gaussian sources. The resulting inlier-based ICA (IBICA) is outlier-robust by construction and can be used for standard ICA as well as for overcomplete ICA (i.e. more source signals than observed signals). (c) 2005 Wiley Periodicals, Inc Y1 - 2005 SN - 0899-9457 ER - TY - JOUR A1 - Lemm, Steven A1 - Blankertz, Benjamin A1 - Curio, Gabriel A1 - Müller, Klaus-Robert T1 - Spatio-spectral filters for improving the classification of single trial EEG N2 - Data recorded in electroencephalogram (EEG)-based brain-computer interface experiments is generally very noisy, non-stationary, and contaminated with artifacts that can deteriorate discrimination/classification methods. In this paper, we extend the common spatial pattern (CSP) algorithm with the aim to alleviate these adverse effects. In particular, we suggest an extension of CSP to the state space, which utilizes the method of time delay embedding. As we will show, this allows for individually tuned frequency filters at each electrode position and, thus, yields an improved and more robust machine learning procedure. The advantages of the proposed method over the original CSP method are verified in terms of an improved information transfer rate (bits per trial) on a set of EEG-recordings from experiments of imagined limb movements Y1 - 2005 SN - 0018-9294 ER - TY - JOUR A1 - Willig, Andreas A1 - Matheus, K. A1 - Wolisz, A. T1 - Wireless technology in industrial networks N2 - With the success of wireless technologies in consumer electronics, standard wireless technologies are envisioned for the deployment in industrial environments as well. Industrial applications involving mobile subsystems or just the desire to save cabling make wireless technologies attractive. Nevertheless, these applications often have stringent requirements on reliability and timing. In wired environments, timing and reliability are well catered for by fieldbus systems (which are a mature technology designed to enable communication between digital controllers and the sensors and actuators interfacing to a physical process). When wireless links are included, reliability and timing requirements are significantly more difficult to meet, due to the adverse properties of the radio channels. In this paper we thus discuss some key issues coming up in wireless fieldbus and wireless industrial communication systems:1)fundamental problems like achieving timely and reliable transmission despite channel errors; 2) the usage of existing wireless technologies for this specific field of applications; and 3) the creation of hybrid systems in which wireless stations are included into existing wired systems Y1 - 2005 SN - 0018-9219 ER - TY - JOUR A1 - Borchert, P. A1 - Anger, Christian A1 - Schaub, Torsten H. A1 - Truszczynski, M. T1 - Towards systematic benchmarking in answer set programming : the dagstuhl initiative Y1 - 2004 SN - 3-540- 20721-x ER - TY - JOUR A1 - Weske, Mathias A1 - van der Aalst, Wil M. P. A1 - Verbeek, H. M. W. T1 - Advances in business process management Y1 - 2004 SN - 0169-023X ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Two approaches to merging knowledge bases Y1 - 2004 SN - 3-540-23242-7 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - Domain-specific preference for causal reasoning and planning Y1 - 2004 SN - 1-577-35201-7 ER - TY - JOUR A1 - Flöter, André A1 - Selbig, Joachim A1 - Schaub, Torsten H. T1 - Finding metabolic pathways in decision forests Y1 - 2004 SN - 3-540-23221-4 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Consistency-based approaches to merging knowledge based : preliminary report Y1 - 2004 UR - http://www.pims.math.ca/science/2004/NMR/papers/paper17.pdf SN - 92-990021-0-X ER - TY - JOUR A1 - Nicolelis, Miguel Angelo L. A1 - Birbaumer, Niels A1 - Muller, K. R. T1 - Untitled Y1 - 2004 SN - 0018-9294 ER - TY - JOUR A1 - Bordihn, Henning T1 - Context-freeness of the power of context-free languages is undecidable N2 - The power of a language L is the set of all powers of the words in L. In this paper, the following decision problem is investigated. Given a context-free language L, is the power of L context-free? We show that this problem is decidable for languages over unary alphabets, but it is undecidable whenever languages over alphabets with at least two letters are considered. (C) 2003 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0304-3975 ER - TY - JOUR A1 - Dornhege, Guido A1 - Blankertz, Benjamin A1 - Curio, Gabriel A1 - Müller, Klaus-Robert T1 - Boosting bit rates in noninvasive EEG single-trial classifications by feature combination and multiclass paradigms N2 - Noninvasive electroencephalogram (EEG) recordings provide for easy and safe access to human neocortical processes which can be exploited for a brain-computer interface (BCI). At present, however, the use of BCIs is severely limited by low bit-transfer rates. We systematically analyze and develop two recent concepts, both capable of enhancing the information gain from multichannel scalp EEG recordings: 1) the combination of classifiers, each specifically tailored for different physiological phenomena, e.g., slow cortical potential shifts, such as the premovement Bereitschaftspotential or differences in spatio-spectral distributions of brain activity (i.e., focal event-related desynchronizations) and 2) behavioral paradigms inducing the subjects to generate one out of several brain states (multiclass approach) which all bare a distinctive spatio-temporal signature well discriminable in the standard scalp EEG. We derive information-theoretic predictions and demonstrate their relevance in experimental data. We will show that a suitably arranged interaction between these concepts can significantly boost BCI performances Y1 - 2004 ER - TY - JOUR A1 - Blankertz, Benjamin A1 - Müller, Klaus-Robert A1 - Curio, Gabriel A1 - Vaughan, Theresa M. A1 - Schalk, Gerwin A1 - Wolpaw, Jonathan R. A1 - Schlogl, Alois A1 - Neuper, Christa A1 - Pfurtscheller, Gert A1 - Hinterberger, Thilo A1 - Schroder, Michael A1 - Birbaumer, Niels T1 - The BCI competition 2003 : Progress and perspectives in detection and discrimination of EEG single trials N2 - Interest in developing a new method of man-to-machine communication-a brain-computer interface (BCI)-has grown steadily over the past few decades. BCIs create a new communication channel between the brain and an output device by bypassing conventional motor output pathways of nerves and muscles. These systems use signals recorded from the scalp, the surface of the cortex, or from inside the brain to enable users to control a variety of applications including simple word-processing software and orthotics. BCI technology could therefore provide a new communication and control option for individuals who cannot otherwise express their wishes to the outside world. Signal processing and classification methods are essential tools in the development of improved BCI technology. We organized the BCI Competition 2003 to evaluate the current state of the art of these tools. Four laboratories well versed in EEG-based BCI research provided six data sets in a documented format. We made these data sets (i.e., labeled training sets and unlabeled test sets) and their descriptions available on the Internet. The goal in the competition was to maximize the performance measure for the test labels. Researchers worldwide tested their algorithms and competed for the best classification results. This paper describes the six data sets and the results and function of the most successful algorithms Y1 - 2004 SN - 0018-9294 ER - TY - JOUR A1 - Flöter, André A1 - Nicolas, Jacques A1 - Schaub, Torsten H. A1 - Selbig, Joachim T1 - Threshold extraction in metabolite concentration data N2 - Motivation: Continued development of analytical techniques based on gas chromatography and mass spectrometry now facilitates the generation of larger sets of metabolite concentration data. An important step towards the understanding of metabolite dynamics is the recognition of stable states where metabolite concentrations exhibit a simple behaviour. Such states can be characterized through the identification of significant thresholds in the concentrations. But general techniques for finding discretization thresholds in continuous data prove to be practically insufficient for detecting states due to the weak conditional dependences in concentration data. Results: We introduce a method of recognizing states in the framework of decision tree induction. It is based upon a global analysis of decision forests where stability and quality are evaluated. It leads to the detection of thresholds that are both comprehensible and robust. Applied to metabolite concentration data, this method has led to the discovery of hidden states in the corresponding variables. Some of these reflect known properties of the biological experiments, and others point to putative new states Y1 - 2004 ER - TY - JOUR A1 - Harmeling, Stefan A1 - Meinecke, Frank C. A1 - Müller, Klaus-Robert T1 - Injecting noise for analysing the stability of ICA components N2 - Usually, noise is considered to be destructive. We present a new method that constructively injects noise to assess the reliability and the grouping structure of empirical ICA component estimates. Our method can be viewed as a Monte-Carlo-style approximation of the curvature of some performance measure at the solution. Simulations show that the true root-mean-squared angle distances between the real sources and the source estimates can be approximated well by our method. In a toy experiment, we see that we are also able to reveal the underlying grouping structure of the extracted ICA components. Furthermore, an experiment with fetal ECG data demonstrates that our approach is useful for exploratory data analysis of real-world data. (C) 2003 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0165-1684 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Wang, Kewen T1 - A classification and survey of preference handling approchaches in nonmonotonic reasoning N2 - In recent years, there has been a large amount of disparate work concerning the representation and reasoning with qualitative preferential information by means of approaches to nonmonotonic reasoning. Given the variety of underlying systems, assumptions, motivations, and intuitions, it is difficult to compare or relate one approach with another. Here, we present an overview and classification for approaches to dealing with preference. A set of criteria for classifying approaches is given, followed by a set of desiderata that an approach might be expected to satisfy. A comprehensive set of approaches is subsequently given and classified with respect to these sets of underlying principles Y1 - 2004 SN - 0824-7935 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Reasoning with sets of preferences in default logic N2 - We present a general approach for representing and reasoning with sets of defaults in default logic, focusing on reasoning about preferences among sets of defaults. First, we consider how to control the application of a set of defaults so that either all apply (if possible) or none do (if not). From this, an approach to dealing with preferences among sets of default rules is developed. We begin with an ordered default theory, consisting of a standard default theory, but with possible preferences on sets of rules. This theory is transformed into a second, standard default theory wherein the preferences are respected. The approach differs from other work, in that we obtain standard default theories and do not rely on prioritized versions of default logic. In practical terms this means we can immediately use existing default logic theorem provers for an implementation. Also, we directly generate just those extensions containing the most preferred applied rules; in contrast, most previous approaches generate all extensions, then select the most preferred. In a major application of the approach, we show how semimonotonic default theories can be encoded so that reasoning can be carried out at the object level. With this, we can reason about default extensions from within the framework of a standard default logic. Hence one can encode notions such as skeptical and credulous conclusions, and can reason about such conclusions within a single extension Y1 - 2004 SN - 0824-7935 ER - TY - JOUR A1 - Goessel, Michael A1 - Chakrabarty, Krishnendu A1 - Ocheretnij, V. A1 - Leininger, Andreas T1 - A signature analysis technique for the identification of failing vectors with application to Scan-BIST N2 - We present a new technique for uniquely identifying a single failing vector in an interval of test vectors. This technique is applicable to combinational circuits and for scan-BIST in sequential circuits with multiple scan chains. The proposed method relies on the linearity properties of the MISR and on the use of two test sequences, which are both applied to the circuit under test. The second test sequence is derived from the first in a straightforward manner and the same test pattern source is used for both test sequences. If an interval contains only a single failing vector, the algebraic analysis is guaranteed to identify it. We also show analytically that if an interval contains two failing vectors, the probability that this case is interpreted as one failing vector is very low. We present experimental results for the ISCAS benchmark circuits to demonstrate the use of the proposed method for identifying failing test vectors Y1 - 2004 SN - 0923-8174 ER - TY - JOUR A1 - Müller, Klaus-Robert A1 - Vigario, R. A1 - Meinecke, Frank C. A1 - Ziehe, Andreas T1 - Blind source separation techniques for decomposing event-related brain signals N2 - Recently blind source separation (BSS) methods have been highly successful when applied to biomedical data. This paper reviews the concept of BSS and demonstrates its usefulness in the context of event-related MEG measurements. In a first experiment we apply BSS to artifact identification of raw MEG data and discuss how the quality of the resulting independent component projections can be evaluated. The second part of our study considers averaged data of event-related magnetic fields. Here, it is particularly important to monitor and thus avoid possible overfitting due to limited sample size. A stability assessment of the BSS decomposition allows to solve this task and an additional grouping of the BSS components reveals interesting structure, that could ultimately be used for gaining a better physiological modeling of the data Y1 - 2004 SN - 0218-1274 ER - TY - JOUR A1 - Sugiyama, Masashi A1 - Kawanabe, Motoaki A1 - Müller, Klaus-Robert T1 - Trading variance reduction with unbiasedness : the regularized subspace information criterion for robust model selection in kernel regression N2 - A well-known result by Stein (1956) shows that in particular situations, biased estimators can yield better parameter estimates than their generally preferred unbiased counterparts. This letter follows the same spirit, as we will stabilize the unbiased generalization error estimates by regularization and finally obtain more robust model selection criteria for learning. We trade a small bias against a larger variance reduction, which has the beneficial effect of being more precise on a single training set. We focus on the subspace information criterion (SIC), which is an unbiased estimator of the expected generalization error measured by the reproducing kernel Hilbert space norm. SIC can be applied to the kernel regression, and it was shown in earlier experiments that a small regularization of SIC has a stabilization effect. However, it remained open how to appropriately determine the degree of regularization in SIC. In this article, we derive an unbiased estimator of the expected squared error, between SIC and the expected generalization error and propose determining the degree of regularization of SIC such that the estimator of the expected squared error is minimized. Computer simulations with artificial and real data sets illustrate that the proposed method works effectively for improving the precision of SIC, especially in the high-noise-level cases. We furthermore compare the proposed method to the original SIC, the cross-validation, and an empirical Bayesian method in ridge parameter selection, with good results Y1 - 2004 SN - 0899-7667 ER - TY - JOUR A1 - Ziehe, Andreas A1 - Kawanabe, Motoaki A1 - Harmeling, Stefan T1 - Blind separation of post-nonlinear mixtures using linearizing transformations and temporal decorrelation N2 - We propose two methods that reduce the post-nonlinear blind source separation problem (PNL-BSS) to a linear BSS problem. The first method is based on the concept of maximal correlation: we apply the alternating conditional expectation (ACE) algorithm-a powerful technique from nonparametric statistics-to approximately invert the componentwise nonlinear functions. The second method is a Gaussianizing transformation, which is motivated by the fact that linearly mixed signals before nonlinear transformation are approximately Gaussian distributed. This heuristic, but simple and efficient procedure works as good as the ACE method. Using the framework provided by ACE, convergence can be proven. The optimal transformations obtained by ACE coincide with the sought-after inverse functions of the nonlinearitics. After equalizing the nonlinearities, temporal decorrelation separation (TDSEP) allows us to recover the source signals. Numerical simulations testing "ACE-TD" and "Gauss-TD" on realistic examples are performed with excellent results Y1 - 2004 SN - 1532-4435 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans T1 - A framework for compiling preferences in logic programs Y1 - 2003 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Reasoning credulously and skeptically within a single extension Y1 - 2003 ER - TY - JOUR A1 - Linke, Thomas T1 - Suitable graphs for answer set programming Y1 - 2003 UR - http://sunsite.informatik.rwth-aachen.de/Publications/CEUR-WS/Vol-78/ SN - 1613-0073 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Linke, Thomas A1 - Schaub, Torsten H. T1 - Graphs and colorings for answer set programming : abridged report Y1 - 2003 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/kolisch03a.pdf SN - 1613-0073 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - On the relation between Reiterïs default logic and its (major) variants Y1 - 2003 SN - 3-540- 409494-5 ER - TY - JOUR A1 - Besnard, Philippe A1 - Mercer, Robert E. A1 - Schaub, Torsten H. T1 - Optimality theory throught default logic Y1 - 2003 SN - 3-540-20059-2 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Schaub, Torsten H. A1 - Linke, Thomas T1 - Graphs and colorings for answer set programming with prefernces : preliminary report Y1 - 2003 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/koschli03a.pdf SN - 1613-0073 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Gharib, Mona A1 - Mercer, Robert E. A1 - Risch, V. A1 - Schaub, Torsten H. T1 - Lukaszewicz-style answer set programming : a preliminary report Y1 - 2003 UR - http://sunsite.informatik.rwth-aachen.de/Publications/CEUR-WS/Vol-78/ SN - 1613-0073 ER - TY - JOUR A1 - Linke, Thomas T1 - Using nested logic programs for answer set programming Y1 - 2003 UR - http://sunsite.informatik.rwth-aachen.de/Publications/CEUR-WS/Vol-78/ SN - 1613-0073 ER - TY - JOUR A1 - Schaub, Torsten H. A1 - Wang, Kewen T1 - A semantic framework for prefernce handling in answer set programming Y1 - 2003 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - A concictency-based paradigm for belief change Y1 - 2003 SN - 0004-3702 ER - TY - JOUR A1 - Schaub, Torsten H. T1 - Antwortmengenprogrammierung Y1 - 2003 ER - TY - JOUR A1 - Konczak, Kathrin A1 - Schaub, Torsten H. A1 - Linke, Thomas T1 - Graphs and colorings for answer set programming with preferences N2 - The integration of preferences into answer set programming constitutes an important practical device for distinguishing certain preferred answer sets from non-preferred ones. To this end, we elaborate upon rule dependency graphs and their colorings for characterizing different preference handling strategies found in the literature. We start from a characterization of (three types of) preferred answer sets in terms of totally colored dependency graphs. In particular, we demonstrate that this approach allows us to capture all three approaches to preferences in a uniform setting by means of the concept of a height function. In turn, we exemplarily develop an operational characterization of preferred answer sets in terms of operators on partial colorings for one particular strategy. In analogy to the notion of a derivation in proof theory, our operational characterization is expressed as a (non-deterministically formed) sequence of colorings, gradually turning an uncolored graph into a totally colored one Y1 - 2003 SN - 0169-2968 ER - TY - JOUR A1 - Flöter, André A1 - Nicolas, Jacques A1 - Schaub, Torsten H. A1 - Selbig, Joachim T1 - Threshold extraction in metabolite concentration data Y1 - 2003 UR - http://www.cs.uni-potsdam.de/wv/pdfformat/floeterGCB2003.pdf ER - TY - JOUR A1 - Anger, Christian A1 - Konczak, Kathrin A1 - Linke, Thomas T1 - NoMoRe: A system for non-monotonic reasoning with logic programs under answer set semantics Y1 - 2002 SN - 3-540-42254-4 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. A1 - Tompits, Hans A1 - Wang, Kewen T1 - Towards a classification of preference handling approaches in nonmonotonic reasoning Y1 - 2002 SN - 1-577-35166-5 ER - TY - JOUR A1 - Besnard, Philippe A1 - Mercer, Robert E. A1 - Schaub, Torsten H. T1 - Optimality Theory via Default Logic Y1 - 2002 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Schaub, Torsten H. T1 - Reasoning credulously and skeptically within a single extension Y1 - 2002 ER - TY - JOUR A1 - Delgrande, James Patrick A1 - Hunter, Anthony A1 - Schaub, Torsten H. T1 - COBA: a consistency-based belief revision system Y1 - 2002 SN - 3-540-44190-5 ER - TY - JOUR A1 - Schaub, Torsten H. A1 - Wang, T. T1 - Preferred well-founded semantics for logic programming by alternating fixpoints : preliminary report Y1 - 2002 ER - TY - JOUR A1 - Linke, Thomas A1 - Anger, Christian A1 - Konczak, Kathrin T1 - More on nomore Y1 - 2002 SN - 3-540-44190-5 ER - TY - JOUR A1 - Döllner, Jürgen Roland Friedrich T1 - Geospatial digital rights management in geovisualization N2 - Geovisualization offers powerful tools, techniques, and strategies to present, explore, analyze, and manage geoinformation. Interactive geovirtual environments such as virtual 3D maps or virtual 3D city models, however, raise the question how to control geodata usage and distribution. We present a concept for embedding digital rights in geovisualizations. It is based on geo-documents, an object-oriented scheme to specify a wide range of geo visualizations. Geo-documents are assembled by building blocks categorized into presentation, structure, interaction, animation, and Digital Rights Management (DRM) classes. DRM objects allow for defining permissions and constraints for all objects contained in geo-documents. In this way, authors of geo visualizations can control how their geo-documents are used, personalized, and redistributed by users. The strengths of the presented concept include the ability to integrate heterogeneous 2D and 3D geodata within a compact design scheme and the ability to cope with privacy, security, and copyright issues. Embedded digital rights in geovisualizations can be applied to improve the usability of geodata user interfaces, to implement publisher-subscriber communication systems for geodata, and to establish business models for geodata trading systems Y1 - 2005 SN - 0008-7041 ER - TY - JOUR A1 - Nienhaus, Marc A1 - Döllner, Jürgen Roland Friedrich T1 - Depicting dynamics using principles of visual art and narration's Y1 - 2005 SN - 0272-1716 ER - TY - JOUR A1 - Delikostidis, Ioannis A1 - Engel, Juri A1 - Retsios, Bas A1 - van Elzakker, Corne P. J. M. A1 - Kraak, Menno-Jan A1 - Döllner, Jürgen Roland Friedrich T1 - Increasing the usability of pedestrian navigation interfaces by means of landmark visibility analysis JF - The journal of navigation N2 - Communicating location-specific information to pedestrians is a challenging task which can be aided by user-friendly digital technologies. In this paper, landmark visibility analysis, as a means for developing more usable pedestrian navigation systems, is discussed. Using an algorithmic framework for image-based 3D analysis, this method integrates a 3D city model with identified landmarks and produces raster visibility layers for each one. This output enables an Android phone prototype application to indicate the visibility of landmarks from the user's actual position. Tested in the field, the method achieves sufficient accuracy for the context of use and improves navigation efficiency and effectiveness. KW - Pedestrian navigation KW - Landmark visibility KW - User-centred design KW - Usability testing Y1 - 2013 U6 - https://doi.org/10.1017/S0373463313000209 SN - 0373-4633 VL - 66 IS - 4 SP - 523 EP - 537 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Richter, Rico A1 - Kyprianidis, Jan Eric A1 - Döllner, Jürgen Roland Friedrich T1 - Out-of-core GPU-based change detection in massive 3D point clouds JF - Transactions in GIS N2 - If sites, cities, and landscapes are captured at different points in time using technology such as LiDAR, large collections of 3D point clouds result. Their efficient storage, processing, analysis, and presentation constitute a challenging task because of limited computation, memory, and time resources. In this work, we present an approach to detect changes in massive 3D point clouds based on an out-of-core spatial data structure that is designed to store data acquired at different points in time and to efficiently attribute 3D points with distance information. Based on this data structure, we present and evaluate different processing schemes optimized for performing the calculation on the CPU and GPU. In addition, we present a point-based rendering technique adapted for attributed 3D point clouds, to enable effective out-of-core real-time visualization of the computation results. Our approach enables conclusions to be drawn about temporal changes in large highly accurate 3D geodata sets of a captured area at reasonable preprocessing and rendering times. We evaluate our approach with two data sets from different points in time for the urban area of a city, describe its characteristics, and report on applications. Y1 - 2013 U6 - https://doi.org/10.1111/j.1467-9671.2012.01362.x SN - 1361-1682 VL - 17 IS - 5 SP - 724 EP - 741 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Paredes, E. G. A1 - Boo, M. A1 - Amor, M. A1 - Bruguera, J. D. A1 - Döllner, Jürgen Roland Friedrich T1 - Extended hybrid meshing algorithm for multiresolution terrain models JF - International journal of geographical information science N2 - Hybrid terrains are a convenient approach for the representation of digital terrain models, integrating heterogeneous data from different sources. In this article, we present a general, efficient scheme for achieving interactive level-of-detail rendering of hybrid terrain models, without the need for a costly preprocessing or resampling of the original data. The presented method works with hybrid digital terrains combining regular grid data and local high-resolution triangulated irregular networks. Since grid and triangulated irregular network data may belong to different datasets, a straightforward combination of both geometries would lead to meshes with holes and overlapping triangles. Our method generates a single multiresolution model integrating the different parts in a coherent way, by performing an adaptive tessellation of the region between their boundaries. Hence, our solution is one of the few existing approaches for integrating different multiresolution algorithms within the same terrain model, achieving a simple interactive rendering of complex hybrid terrains. KW - 3D modeling KW - 3D visualization KW - geovisualization KW - triangulated irregular networks Y1 - 2012 U6 - https://doi.org/10.1080/13658816.2011.615317 SN - 1365-8816 VL - 26 IS - 5 SP - 771 EP - 793 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Hecher, Markus T1 - Treewidth-aware reductions of normal ASP to SAT BT - is normal ASP harder than SAT after all? JF - Artificial intelligence N2 - Answer Set Programming (ASP) is a paradigm for modeling and solving problems for knowledge representation and reasoning. There are plenty of results dedicated to studying the hardness of (fragments of) ASP. So far, these studies resulted in characterizations in terms of computational complexity as well as in fine-grained insights presented in form of dichotomy-style results, lower bounds when translating to other formalisms like propositional satisfiability (SAT), and even detailed parameterized complexity landscapes. A generic parameter in parameterized complexity originating from graph theory is the socalled treewidth, which in a sense captures structural density of a program. Recently, there was an increase in the number of treewidth-based solvers related to SAT. While there are translations from (normal) ASP to SAT, no reduction that preserves treewidth or at least keeps track of the treewidth increase is known. In this paper we propose a novel reduction from normal ASP to SAT that is aware of the treewidth, and guarantees that a slight increase of treewidth is indeed sufficient. Further, we show a new result establishing that, when considering treewidth, already the fragment of normal ASP is slightly harder than SAT (under reasonable assumptions in computational complexity). This also confirms that our reduction probably cannot be significantly improved and that the slight increase of treewidth is unavoidable. Finally, we present an empirical study of our novel reduction from normal ASP to SAT, where we compare treewidth upper bounds that are obtained via known decomposition heuristics. Overall, our reduction works better with these heuristics than existing translations. (c) 2021 Elsevier B.V. All rights reserved. KW - Answer set programming KW - Treewidth KW - Parameterized complexity KW - Complexity KW - analysis KW - Tree decomposition KW - Treewidth-aware reductions Y1 - 2022 U6 - https://doi.org/10.1016/j.artint.2021.103651 SN - 0004-3702 SN - 1872-7921 VL - 304 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Csuhaj-Varjú, Erzsébet A1 - Dassow, Juergen A1 - Vaszil, György T1 - Variants of competence-based derivations in CD grammar systems N2 - In this paper we introduce and study some new cooperation protocols for cooperating distributed (CD) grammar systems. These derivation modes depend on the number of different nonterminals present in the sentential form obtained when a component finished a derivation phase. This measure describes the competence of the grammar on the string (the competence is high if the number of the different nonterminals is small). It is also a measure of the efficiency of the grammar on the given string (a component is more efficient than another one if it is able to decrease the number of nonterminals in the string to a greater extent). We prove that if the underlying derivation mode is the t-mode derivation, then some variants of these systems determine the class of random context ET0L languages. If these CD grammar systems use the k step limited derivations as underlying derivation mode, then they are able to generate any recursively enumerable language. Y1 - 2010 UR - http://www.worldscinet.com/ijfcs/ijfcs.shtml U6 - https://doi.org/10.1142/S0129054110007428 SN - 0129-0541 ER - TY - JOUR A1 - Al Laban, Firas A1 - Reger, Martin A1 - Lucke, Ulrike T1 - Closing the Policy Gap in the Academic Bridge JF - Education sciences N2 - The highly structured nature of the educational sector demands effective policy mechanisms close to the needs of the field. That is why evidence-based policy making, endorsed by the European Commission under Erasmus+ Key Action 3, aims to make an alignment between the domains of policy and practice. Against this background, this article addresses two issues: First, that there is a vertical gap in the translation of higher-level policies to local strategies and regulations. Second, that there is a horizontal gap between educational domains regarding the policy awareness of individual players. This was analyzed in quantitative and qualitative studies with domain experts from the fields of virtual mobility and teacher training. From our findings, we argue that the combination of both gaps puts the academic bridge from secondary to tertiary education at risk, including the associated knowledge proficiency levels. We discuss the role of digitalization in the academic bridge by asking the question: which value does the involved stakeholders expect from educational policies? As a theoretical basis, we rely on the model of value co-creation for and by stakeholders. We describe the used instruments along with the obtained results and proposed benefits. Moreover, we reflect on the methodology applied, and we finally derive recommendations for future academic bridge policies. KW - policy evaluation KW - higher education KW - virtual mobility KW - teacher training Y1 - 2022 U6 - https://doi.org/10.3390/educsci12120930 SN - 2227-7102 VL - 12 IS - 12 PB - MDPI CY - Basel ER - TY - JOUR A1 - Gebser, Martin A1 - Obermeier, Philipp A1 - Schaub, Torsten H. A1 - Ratsch-Heitmann, Michel A1 - Runge, Mario T1 - Routing driverless transport vehicles in car assembly with answer set programming JF - Theory and practice of logic programming N2 - Automated storage and retrieval systems are principal components of modern production and warehouse facilities. In particular, automated guided vehicles nowadays substitute human-operated pallet trucks in transporting production materials between storage locations and assembly stations. While low-level control systems take care of navigating such driverless vehicles along programmed routes and avoid collisions even under unforeseen circumstances, in the common case of multiple vehicles sharing the same operation area, the problem remains how to set up routes such that a collection of transport tasks is accomplished most effectively. We address this prevalent problem in the context of car assembly at Mercedes-Benz Ludwigsfelde GmbH, a large-scale producer of commercial vehicles, where routes for automated guided vehicles used in the production process have traditionally been hand-coded by human engineers. Such adhoc methods may suffice as long as a running production process remains in place, while any change in the factory layout or production targets necessitates tedious manual reconfiguration, not to mention the missing portability between different production plants. Unlike this, we propose a declarative approach based on Answer Set Programming to optimize the routes taken by automated guided vehicles for accomplishing transport tasks. The advantages include a transparent and executable problem formalization, provable optimality of routes relative to objective criteria, as well as elaboration tolerance towards particular factory layouts and production targets. Moreover, we demonstrate that our approach is efficient enough to deal with the transport tasks evolving in realistic production processes at the car factory of Mercedes-Benz Ludwigsfelde GmbH. KW - automated guided vehicle routing KW - car assembly operations KW - answer set programming Y1 - 2018 U6 - https://doi.org/10.1017/S1471068418000182 SN - 1471-0684 SN - 1475-3081 VL - 18 IS - 3-4 SP - 520 EP - 534 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Hollmann, Susanne A1 - Frohme, Marcus A1 - Endrullat, Christoph A1 - Kremer, Andreas A1 - D’Elia, Domenica A1 - Regierer, Babette A1 - Nechyporenko, Alina T1 - Ten simple rules on how to write a standard operating procedure JF - PLOS Computational Biology N2 - Research publications and data nowadays should be publicly available on the internet and, theoretically, usable for everyone to develop further research, products, or services. The long-term accessibility of research data is, therefore, fundamental in the economy of the research production process. However, the availability of data is not sufficient by itself, but also their quality must be verifiable. Measures to ensure reuse and reproducibility need to include the entire research life cycle, from the experimental design to the generation of data, quality control, statistical analysis, interpretation, and validation of the results. Hence, high-quality records, particularly for providing a string of documents for the verifiable origin of data, are essential elements that can act as a certificate for potential users (customers). These records also improve the traceability and transparency of data and processes, therefore, improving the reliability of results. Standards for data acquisition, analysis, and documentation have been fostered in the last decade driven by grassroot initiatives of researchers and organizations such as the Research Data Alliance (RDA). Nevertheless, what is still largely missing in the life science academic research are agreed procedures for complex routine research workflows. Here, well-crafted documentation like standard operating procedures (SOPs) offer clear direction and instructions specifically designed to avoid deviations as an absolute necessity for reproducibility. Therefore, this paper provides a standardized workflow that explains step by step how to write an SOP to be used as a starting point for appropriate research documentation. Y1 - 2020 VL - 16 IS - 9 PB - PLOS CY - San Francisco ER - TY - JOUR A1 - Gebser, Martin A1 - Kaminski, Roland A1 - Kaufmann, Benjamin A1 - Lühne, Patrick A1 - Obermeier, Philipp A1 - Ostrowski, Max A1 - Romero Davila, Javier A1 - Schaub, Torsten H. A1 - Schellhorn, Sebastian A1 - Wanko, Philipp T1 - The Potsdam Answer Set Solving Collection 5.0 JF - Künstliche Intelligenz N2 - The Potsdam answer set solving collection, or Potassco for short, bundles various tools implementing and/or applying answer set programming. The article at hand succeeds an earlier description of the Potassco project published in Gebser et al. (AI Commun 24(2):107-124, 2011). Hence, we concentrate in what follows on the major features of the most recent, fifth generation of the ASP system clingo and highlight some recent resulting application systems. Y1 - 2018 U6 - https://doi.org/10.1007/s13218-018-0528-x SN - 0933-1875 SN - 1610-1987 VL - 32 IS - 2-3 SP - 181 EP - 182 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Haubelt, Christian A1 - Neubauer, Kai A1 - Schaub, Torsten H. A1 - Wanko, Philipp T1 - Design space exploration with answer set programming JF - Künstliche Intelligenz N2 - The aim of our project design space exploration with answer set programming is to develop a general framework based on Answer Set Programming (ASP) that finds valid solutions to the system design problem and simultaneously performs Design Space Exploration (DSE) to find the most favorable alternatives. We leverage recent developments in ASP solving that allow for tight integration of background theories to create a holistic framework for effective DSE. Y1 - 2018 U6 - https://doi.org/10.1007/s13218-018-0530-3 SN - 0933-1875 SN - 1610-1987 VL - 32 IS - 2-3 SP - 205 EP - 206 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Prescher, Denise A1 - Bornschein, Jens A1 - Köhlmann, Wiebke A1 - Weber, Gerhard T1 - Touching graphical applications BT - bimanual tactile interaction on the HyperBraille pin-matrix display JF - Universal Access in the Information Society N2 - Novel two-dimensional tactile displays enable blind users to not only get access to the textual but also to the graphical content of a graphical user interface. Due to the higher amount of information that can be presented in parallel, orientation and exploration can be more complex. In this paper we present the HyperBraille system, which consists of a pin-matrix device as well as a graphical screen reader providing the user with appropriate presentation and interaction possibilities. To allow for a detailed analysis of bimanual interaction strategies on a pin-matrix device, we conducted two user studies with a total of 12 blind people. The task was to fill in .pdf forms on the pin-matrix device by using different input methods, namely gestures, built-in hardware buttons as well as a conventional PC keyboard. The forms were presented in a semigraphic view type that not only contains Braille but also tactile widgets in a spatial arrangement. While completion time and error rate partly depended on the chosen input method, the usage of special reading strategies seemed to be independent of it. A direct comparison of the system and a conventional assistive technology (screen reader with single-line Braille device) showed that interaction on the pin-matrix device can be very efficient if the user is trained. The two-dimensional output can improve access to .pdf forms with insufficient accessibility as the mapping of input controls and the corresponding labels can be supported by a spatial presentation. KW - Planar tactile display KW - Blind users KW - pdf forms KW - Screen reader KW - Gesture input KW - Key input Y1 - 2018 U6 - https://doi.org/10.1007/s10209-017-0538-8 SN - 1615-5289 SN - 1615-5297 VL - 17 IS - 2 SP - 391 EP - 409 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Metref, Sammy A1 - Cosme, Emmanuel A1 - Le Sommer, Julien A1 - Poel, Nora A1 - Brankart, Jean-Michel A1 - Verron, Jacques A1 - Gomez Navarro, Laura T1 - Reduction of spatially structured errors in Wide-Swath altimetric satellite data using data assimilation JF - Remote sensing N2 - The Surface Water and Ocean Topography (SWOT) mission is a next generation satellite mission expected to provide a 2 km-resolution observation of the sea surface height (SSH) on a two-dimensional swath. Processing SWOT data will be challenging because of the large amount of data, the mismatch between a high spatial resolution and a low temporal resolution, and the observation errors. The present paper focuses on the reduction of the spatially structured errors of SWOT SSH data. It investigates a new error reduction method and assesses its performance in an observing system simulation experiment. The proposed error-reduction method first projects the SWOT SSH onto a subspace spanned by the SWOT spatially structured errors. This projection is removed from the SWOT SSH to obtain a detrended SSH. The detrended SSH is then processed within an ensemble data assimilation analysis to retrieve a full SSH field. In the latter step, the detrending is applied to both the SWOT data and an ensemble of model-simulated SSH fields. Numerical experiments are performed with synthetic SWOT observations and an ensemble from a North Atlantic, 1/60 degrees simulation of the ocean circulation (NATL60). The data assimilation analysis is carried out with an ensemble Kalman filter. The results are assessed with root mean square errors, power spectrum density, and spatial coherence. They show that a significant part of the large scale SWOT errors is reduced. The filter analysis also reduces the small scale errors and allows for an accurate recovery of the energy of the signal down to 25 km scales. In addition, using the SWOT nadir data to adjust the SSH detrending further reduces the errors. KW - SWOT KW - correlated errors KW - OSSE KW - projection KW - detrending KW - ensemble kalman filter Y1 - 2019 U6 - https://doi.org/10.3390/rs11111336 SN - 2072-4292 VL - 11 IS - 11 PB - MDPI CY - Basel ER - TY - JOUR A1 - Dimopoulos, Yannis A1 - Gebser, Martin A1 - Lühne, Patrick A1 - Romero Davila, Javier A1 - Schaub, Torsten H. T1 - plasp 3 BT - Towards Effective ASP Planning JF - Theory and practice of logic programming N2 - We describe the new version of the Planning Domain Definition Language (PDDL)-to-Answer Set Programming (ASP) translator plasp. First, it widens the range of accepted PDDL features. Second, it contains novel planning encodings, some inspired by Satisfiability Testing (SAT) planning and others exploiting ASP features such as well-foundedness. All of them are designed for handling multivalued fluents in order to capture both PDDL as well as SAS planning formats. Third, enabled by multishot ASP solving, it offers advanced planning algorithms also borrowed from SAT planning. As a result, plasp provides us with an ASP-based framework for studying a variety of planning techniques in a uniform setting. Finally, we demonstrate in an empirical analysis that these techniques have a significant impact on the performance of ASP planning. KW - knowledge representation and nonmonotonic reasoning KW - technical notes and rapid communications KW - answer set programming KW - automated planning KW - action and change Y1 - 2019 U6 - https://doi.org/10.1017/S1471068418000583 SN - 1471-0684 SN - 1475-3081 VL - 19 IS - 3 SP - 477 EP - 504 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Pousttchi, Key A1 - Gleiß, Alexander T1 - Surrounded by middlemen - how multi-sided platforms change the insurance industry JF - Electron Markets N2 - Multi-sided platforms (MSP) strongly affect markets and play a crucial part within the digital and networked economy. Although empirical evidence indicates their occurrence in many industries, research has not investigated the game-changing impact of MSP on traditional markets to a sufficient extent. More specifically, we have little knowledge of how MSP affect value creation and customer interaction in entire markets, exploiting the potential of digital technologies to offer new value propositions. Our paper addresses this research gap and provides an initial systematic approach to analyze the impact of MSP on the insurance industry. For this purpose, we analyze the state of the art in research and practice in order to develop a reference model of the value network for the insurance industry. On this basis, we conduct a case-study analysis to discover and analyze roles which are occupied or even newly created by MSP. As a final step, we categorize MSP with regard to their relation to traditional insurance companies, resulting in a classification scheme with four MSP standard types: Competition, Coordination, Cooperation, Collaboration. KW - Multi-sided platforms KW - Insurance industry KW - Value network KW - Digitalization KW - Customer ownership Y1 - 2019 U6 - https://doi.org/10.1007/s12525-019-00363-w SN - 1019-6781 SN - 1422-8890 VL - 29 IS - 4 SP - 609 EP - 629 PB - Springer CY - Heidelberg ER -