@article{Konczak2006, author = {Konczak, Kathrin}, title = {Weak order equivalence for Logic Programs with Prefernces}, year = {2006}, language = {en} } @article{KonczakVogel2005, author = {Konczak, Kathrin and Vogel, Ralf}, title = {Abduction and Preferences in Linguistics}, year = {2005}, language = {en} } @article{CaludeJurgensen2005, author = {Calude, C. S. and Jurgensen, Helmut}, title = {Is complexity a source of incompleteness?}, issn = {0196-8858}, year = {2005}, abstract = {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}, language = {en} } @article{Bordihn2005, author = {Bordihn, Henning}, title = {On the number of components in cooperating distributed grammar systems}, issn = {0304-3975}, year = {2005}, abstract = {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}, language = {en} } @article{BeerenwinkelSingLengaueretal.2005, author = {Beerenwinkel, Niko and Sing, Tobias and Lengauer, Thomas and Rahnenfuhrer, Joerg and Roomp, Kirsten and Savenkov, Igor and Fischer, Roman and Hoffmann, Daniel and Selbig, Joachim and Korn, Klaus and Walter, Hauke and Berg, Thomas and Braun, Patrick and Faetkenheuer, Gerd and Oette, Mark and Rockstroh, Juergen and Kupfer, Bernd and Kaiser, Rolf and Daeumer, Martin}, title = {Computational methods for the design of effective therapies against drug resistant HIV strains}, year = {2005}, abstract = {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}, language = {en} } @article{BrzozowskiJuergensen2005, author = {Brzozowski, J. A. and J{\"u}rgensen, Helmut}, title = {Representation of semiautomata by canonical words and equivalences}, issn = {0129-0541}, year = {2005}, abstract = {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}, language = {en} } @article{BordihnHolzerKutrib2005, author = {Bordihn, Henning and Holzer, Markus and Kutrib, Martin}, title = {Unsolvability levels of operation problems for subclasses of context-free languages}, issn = {0129-0541}, year = {2005}, abstract = {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}, language = {en} } @article{BruggemeierDovifatKubisch2005, author = {Bruggemeier, M. and Dovifat, A. and Kubisch, D.}, title = {Micropolitical innovation arenas as a tool for analyzing innovation processes in the context of electronic government}, issn = {0937-6429}, year = {2005}, abstract = {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}, language = {en} } @article{MeineckeZieheKurthsetal.2005, author = {Meinecke, Frank C. and Ziehe, Andreas and Kurths, J{\"u}rgen and M{\"u}ller, Klaus-Robert}, title = {Measuring phase synchronization of superimposed signals}, issn = {0031-9007}, year = {2005}, abstract = {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}, language = {en} } @article{ScholzKaplanGuyetal.2005, author = {Scholz, Matthias and Kaplan, F. and Guy, C. L. and Kopka, Joachim and Selbig, Joachim}, title = {Non-linear PCA : a missing data approach}, issn = {1367-4803}, year = {2005}, abstract = {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}, language = {en} }