@misc{GottwaldTolksdorf2009, author = {Gottwald, Susanne and Tolksdorf, Robert}, title = {Planning Teams with Semantic Web Technologies}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11523}, number = {09-33}, year = {2009}, abstract = {When planning teams for projects with specific goals, employees of a company have to group together so well, that all necessary knowledge for conquering the project's challenges are met within the member's skills. A tool that facilitates semantic web technologies can support the team recruiter, who is responsible for chosing the members of the team, in terms of finding the most efficient combinations of the company's employees based on their expertises.}, language = {en} } @misc{TsarevWolf2009, author = {Tsarev, Sergey and Wolf, Thomas}, title = {Hyperdeterminants as integrable discrete systems}, issn = {1438-0064}, arxiv = {http://arxiv.org/abs/0903.3864}, doi = {10.1088/1751-8113/42/45/454023}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11292}, number = {09-17}, year = {2009}, abstract = {We give the basic definitions and some theoretical results about hyperdeterminants, introduced by A.~Cayley in 1845. We prove integrability (understood as \$4d\$-consistency) of a nonlinear difference equation defined by the \$2 \times 2 \times 2\$ - hyperdeterminant. This result gives rise to the following hypothesis: the difference equations defined by hyperdeterminants of any size are integrable. We show that this hypothesis already fails in the case of the \$2\times 2\times 2\times 2\$ - hyperdeterminant.}, language = {en} } @misc{HermVolz2008, author = {Herm, Karin and Volz, Sibylle}, title = {The Library Search Engine: A Smart Solution for Integrating Resources Beyond Library Holdings}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-10893}, number = {08-37}, year = {2008}, abstract = {The Cooperative Library Network Berlin-Brandenburg (KOBV), Germany, addresses the problem of how to integrate resources found outside the library and library holdings into a single discovery tool. It presents a solution that uses open source technology to develop a next-generation catalog interface called the Library Search Engine. This pilot project was launched in 2007 with the library of Albert Einstein Science Park, Potsdam. The idea was to design and develop a fast and convenient search tool, integrating local holdings (books, journals, journal articles) as well as relevant scientific subject information such as open access publications and bibliographies.}, language = {en} } @misc{WolfNeun2008, author = {Wolf, Thomas and Neun, Winfried}, title = {About a Computer Algebra based online Mathtest}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-10688}, number = {08-14}, year = {2008}, abstract = {The article describes the online mathematics test {\tt http://lie.math.brocku.ca/mathtest}, its typical applications and experiences gathered.}, language = {en} } @misc{Wolf2010, author = {Wolf, Thomas}, title = {Positions in the Game of Go as Complex Systems}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11823}, number = {10-19}, year = {2010}, abstract = {The paper gathers evidence showing different dimensions of the game of Go: the continuous and discrete nature of the game and different types of relations between state variables happening on ultra local, local, regional, and global scales. Based on these observations a new continuous local model for describing a board position is introduced. This includes the identification of the basic variables describing a board position and the formulation and solution of a dynamical system for their computation. To be usable as a static evaluation function for a game playing program at least group-wide (regional)aspects will have to be incorporated.}, language = {en} } @misc{AncoAliWolf2011, author = {Anco, Stephen and Ali, Sajid and Wolf, Thomas}, title = {Exact solutions of nonlinear partial differential equations by the method of group foliation reduction}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-13171}, number = {11-25}, year = {2011}, abstract = {A novel symmetry method for finding exact solutions to nonlinear PDEs is illustrated by applying it to a semilinear reaction-diffusion equation in multi-dimensions. The method is based on group foliation reduction and employs a separation ansatz to solve an equivalent first-order group foliation system whose independent and dependent variables respectively consist of the invariants and differential invariants of a given one-dimensional group of point symmetries for the reaction-diffusion equation. With this method, solutions of the reaction-diffusion equation are obtained in an explicit form, including group-invariant similarity solutions and travelling-wave solutions, as well as dynamically interesting solutions that are not invariant under any of the point symmetries admitted by this equation.}, language = {en} } @misc{AncoAliWolf2011, author = {Anco, Stephen and Ali, Sajid and Wolf, Thomas}, title = {Symmetry analysis and exact solutions of semilinear heat flow in multi-dimensions}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-13213}, number = {11-26}, year = {2011}, abstract = {A symmetry group method is used to obtain exact solutions for a semilinear radial heat equation in \$n\>1\$ dimensions with a general power nonlinearity. The method involves an ansatz technique to solve an equivalent first-order PDE system of similarity variables given by group foliations of this heat equation, using its admitted group of scaling symmetries. This technique yields explicit similarity solutions as well as other explicit solutions of a more general (non-similarity) form having interesting analytical behavior connected with blow up and dispersion. In contrast, standard similarity reduction of this heat equation gives a semilinear ODE that cannot be explicitly solved by familiar integration techniques such as point symmetry reduction or integrating factors.}, language = {en} } @misc{NeunSturmVigerske2010, author = {Neun, Winfried and Sturm, Thomas and Vigerske, Stefan}, title = {Supporting Global Numerical Optimization of Rational Functions by Generic Symbolic Convexity Tests}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11644}, number = {10-01}, year = {2010}, abstract = {Convexity is an important property in nonlinear optimization since it allows to apply efficient local methods for finding global solutions. We propose to apply symbolic methods to prove or disprove convexity of rational functions over a polyhedral domain. Our algorithms reduce convexity questions to real quantifier elimination problems. Our methods are implemented and publicly available in the open source computer algebra system REDUCE. Our long term goal is to integrate REDUCE as a workhorse'' for symbolic computations into a numerical solver.}, language = {en} } @misc{WolfEfimovskaya2011, author = {Wolf, Thomas and Efimovskaya, Olga}, title = {On integrability of the Kontsevich non-abelian ODE system}, arxiv = {http://arxiv.org/abs/1108.4208v1}, doi = {10.1007/s11005-011-0527-4}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-13113}, number = {11-24}, year = {2011}, abstract = {We consider systems of ODEs with the right hand side being Laurent polynomials in several non-commutative unknowns. In particular, these unknowns could be matrices of arbitrary size. An important example of such a system was proposed by M. Kontsevich. We prove the integrability of the Kontsevich system by finding a Lax pair, corresponding first integrals and commuting flows. We also provide a pre-Hamiltonian operator which maps gradients of integrals for the Kontsevich system to symmetries.}, language = {en} } @misc{BoucharebClementChenetal.2010, author = {Bouchareb, Adel and Cl{\´e}ment, G{\´e}rard and Chen, Chiang-Mei and Wolf, Thomas and Gal'tsov, Dmitri V. and Scherbluk, Nikolai G.}, title = {G_2 generating technique for minimal D=5 supergravity and black rings}, issn = {1438-0064}, arxiv = {http://arxiv.org/abs/0708.2361}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11732}, number = {10-14}, year = {2010}, abstract = {A solution generating technique is developed for \$D=5\$ minimal supergravity with two commuting Killing vectors based on the \$G_2\$ U-duality arising in the reduction of the theory to three dimensions. The target space of the corresponding 3-dimensional sigma-model is the coset \$G_{2(2)}/(SL(2,R)\times SL(2,R))\$. Its isometries constitute the set of solution generating symmetries. These include two electric and two magnetic Harrison transformations with the corresponding two pairs of gauge transformations, three \$SL(2,R) \; S\$-duality transformations, and the three gravitational scale, gauge and Ehlers transformations (altogether 14). We construct a representation of the coset in terms of \$7\times 7\$ matrices realizing the automorphisms of split octonions. Generating a new solution amounts to transforming the coset matrices by one-parametric subgroups of \$G_{2(2)}\$ and subsequently solving the dualization equations. Using this formalism we derive a new charged black ring solution with two independent parameters of rotation.}, language = {en} } @misc{Wolf2010, author = {Wolf, Thomas}, title = {Merging solutions of non-linear algebraic systems}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11769}, number = {10-13}, year = {2010}, abstract = {In solving large polynomial algebraic systems that are too big for standard Gr{\"o}bner basis techniques one way to make progress is to introduce case distinctions. This divide and conquer technique can be beneficial if the algorithms and computer programs know how to take advantage of inequalities. A further hurdle is the form of the resulting general solutions which often have unnecessarily many branches. In this paper we discuss a procedure to merge solutions by dropping inequalities which are associated with them and, if necessary, by re-parametrizing solutions. In the appendix the usefulness of the procedure is demonstrated in the classification of quadratic Hamiltonians with a Lie-Poisson bracket \$e(3)\$. This application required the solution of algebraic systems with over 200 unknowns, 450 equations and between 5000 and 9000 terms.}, language = {en} } @misc{Wolf2010, author = {Wolf, Thomas}, title = {A Dynamical Systems Approach for Static Evaluation in Go}, issn = {1438-0064}, doi = {10.1109/TCIAIG.2011.2141669}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11771}, number = {10-15}, year = {2010}, abstract = {In the paper arguments are given why the concept of static evaluation (SE) has the potential to be a useful extension to Monte Carlo tree search. A new concept of modeling SE through a dynamical system is introduced and strengths and weaknesses are discussed. The general suitability of this approach is demonstrated. A Remark: Among users of the Internet Go server KGS the abbreviation SE is used for 'Score Estimator'. Although different from 'Static Evaluation' a score estimator is easily obtained from static evaluation by adding up probabilities of chains to be alive at the end of the game or points to be owned by White or Black}, language = {en} } @misc{HussinKiselevKrutovetal.2010, author = {Hussin, V. and Kiselev, A. V. and Krutov, A.O. and Wolf, Thomas}, title = {N=2 supersymmetric a=4-KdV hierarchy derived via Gardner's deformation of Kaup-Boussinesq equation}, issn = {1438-0064}, doi = {10.1063/1.3447731}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11787}, number = {10-16}, year = {2010}, abstract = {We consider the problem of constructing Gardner's deformations for the \$N{=}2\$ supersymmetric \$a{=}4\$--\/Korteweg\/--\/de Vries equation; such deformations yield recurrence relations between the super\/-\/Hamiltonians of the hierarchy. We prove the non\/-\/existence \%P.~Mathieu's Open problem on constructing for of supersymmetry\/-\/invariant \%Gardner's deformations that \%solutions, retract to Gardner's formulas for the KdV equation \%whenever it is assumed that, under the \%respective component reduction. \% in the \$N{=}2\$ super\/-\/field. the solutions . At the same time, we propose a two\/-\/step scheme for the recursive production of the integrals of motion for the \$N{=}2\$,\ \$a{=}4\$--\/SKdV. First, we find a new Gardner's deformation of the Kaup\/--\/Boussinesq equation, which is contained in the bosonic limit of the super\/-\/\%\$N{=}2\$,\ \$a{=}4\$--\/SKdV hierarchy. This yields the recurrence relation between the Hamiltonians of the limit, whence we determine the bosonic super\/- /Hamiltonians of the full \$N{=}2\$, \$a{=}4\$--\/SKdV hierarchy.}, language = {en} } @misc{KiselevWolf2010, author = {Kiselev, A. V. and Wolf, Thomas}, title = {Classification of integrable super-systems using the SsTools environment}, issn = {1438-0064}, arxiv = {http://arxiv.org/abs/nlin.SI/0609065}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11792}, number = {10-17}, year = {2010}, abstract = {A classification problem is proposed for supersymmetric \%scaling\/-\/in\-va\-ri\-ant evolutionary PDE that satisfy the assumptions of nonlinearity, nondegeneracy, and homogeneity. Four classes of nonlinear coupled boson\/-\/fermion systems are discovered under the weighting assumption \$|f|=|b|=|D_t|=\oh\$. The syntax of the \Reduce\ package \SsTools, which was used for intermediate computations, and the applicability of its procedures to the calculus of super\/-\/PDE are described.}, language = {en} } @misc{WolfEfimovskaya2010, author = {Wolf, Thomas and Efimovskaya, Olya V.}, title = {Classification of integrable quadratic Hamiltonians on e(3)}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-11807}, number = {10-18}, year = {2010}, abstract = {Linear Poisson brackets on e(3) typical of rigid body dynamics are considered. All quadratic Hamiltonians of Kowalevski type having additional first integral of fourth degree are found. Quantum analogs of these Hamiltonians are listed.}, language = {en} } @misc{KlindtAmrheinMuelleretal.2013, author = {Klindt, Marco and Amrhein, Kilian and M{\"u}ller, Anja and Peters-Kottig, Wolfgang}, title = {Dealing with all the data - Participating in workflows to transform digital data about cultural heritage objects within a digital long-term preservation infrastructure}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-43020}, year = {2013}, abstract = {Cultural heritage institutions are on the verge of making their artefacts available in digital form. During this transition they are faced with conceptual and technical challenges that have only little overlap with their traditional domains but provide them with a lot of opportunities. We aim at empowering them to deal with some of these challenges by designing workflows attached to the data flow within a digital long-term preservation system. The preservation framework processes data by utilising micro-services. These are tailored to accommodate data transformations that can help institutions making their data available if they choose to participate in the interconnected digital world}, language = {en} } @inproceedings{DalitzChrapary2018, author = {Dalitz, Wolfgang and Chrapary, Hagen}, title = {Software Products, Software Versions, Archiving of Software, and swMATH}, booktitle = {Mathematical Software - ICMS 2018}, doi = {10.1007/978-3-319-96418-8_15}, pages = {123 -- 127}, year = {2018}, abstract = {Management of software information is difficult for various reasons. First, software typically cannot be reduced to a single object: information about software is an aggregate of software code, APIs, documentation, installations guides, tutorials, user interfaces, test data, dependencies on hardware and other software, etc. Moreover, secondary information about software, especially use cases and experience with employing the software, is important to communicate. Second, typically named software, which we term here a `software product', is taken to stand for all versions of the software which can have different features and properties and may produced different results from the same input data. Software production is a dynamic process and software development is, increasingly, widely distributed. Therefore GitHub, GitLab, Bitbucket and other platforms for sharing are used. Information about software is alos provided in different locations, on websites, repositories, portals, etc. Each resource provides information about software from a particular point of view, but the information is often not linked together. Therefore swMATH has developed a conception which covers portals and a search engines for mathematical software, persistent and citable landing pages for specific software, and a method for software archiving. Based on the publication-based approach, swMATH collects and analyses semi-automatically the existing information about mathematical software found on the Web and makes it available in a user-oriented way.}, language = {en} } @inproceedings{DalitzChraparySperber2018, author = {Dalitz, Wolfgang and Chrapary, Hagen and Sperber, Wolfram}, title = {Software Knowledge Management and swMATH}, booktitle = {Fachgruppe Didaktik der Mathematik der Universit{\"a}t Paderborn}, doi = {10.17877/DE290R-19281}, pages = {401 -- 404}, year = {2018}, abstract = {Mathematische Software ist heute ein weitverbreitetes Werkzeug in der Forschung, aber auch in der mathematischen Bildung. Die Anzahl mathematischer Softwareprodukte w{\"a}chst, nicht zuletzt durch die Anforderungen der Anwender, stark. Anders als f{\"u}r mathematische Publikationen sind f{\"u}r das Management mathematischer Software viele Fragen offen und werden noch diskutiert, etwa die Standardisierung von Software Zitationen. Der Aufbau einer effizienten Infrastruktur f{\"u}r Software ist eine notwendige Voraussetzung f{\"u}r die {\"U}berpr{\"u}fung von Forschungsergebnissen, die mittels Software erzielt worden sind und wichtig f{\"u}r die Entscheidung, ob eine bestimmte Software zur L{\"o}sung eines Problems verwendet werden soll. Das swMATH [1] Portal gibt einen weitgehend vollst{\"a}ndigen {\"U}berblick {\"u}ber die existierende mathematische Software. Es ist ein Dienst entstanden, der automatisiert die im Web vorhandenen Informationen zu einer Software identifiziert, auswertet und verf{\"u}gbar macht. Der Dienst soll insbesondere durch die Verkn{\"u}pfung mit anderen Quellen, etwa dem Internet Archive, persistente Informationen {\"u}ber ein Software Produkt und dessen Versionen liefern.}, language = {en} } @article{ChraparyDalitzNeunetal.2017, author = {Chrapary, Hagen and Dalitz, Wolfgang and Neun, Winfried and Sperber, Wolfram}, title = {Design, Concepts, and State of the Art of the swMATH Service}, volume = {11}, journal = {Mathematics in Computer Science}, number = {3-4}, doi = {10.1007/s11786-017-0305-5}, pages = {469 -- 481}, year = {2017}, abstract = {In this paper, the concepts and design for an efficient information service for mathematical software and further mathematical research data are presented. The publication-based approach and the web-based approach are the main building blocks of the service and will be discussed. Heuristic methods are used for identification, extraction, and ranking of information about software and other mathematical research data. The methods provide not only information about the research data but also link software and mathematical research data to the scientific context.}, language = {en} } @inproceedings{Klindt2018, author = {Klindt, Marco}, title = {Implications of perceived preservation levels}, volume = {15}, booktitle = {Proceedings of iPres - 15th International Conference on Digital Preservation / Boston, MA, USA / September 24 - 27, 2018}, doi = {10.17605/OSF.IO/M6QA5}, year = {2018}, abstract = {This paper describes and explores the concept of perceived preservation levels and their implications. Perceived preservation levels are a way to communicate preservation policies, options and actions to the various stakeholders in digital preservation a digital preservation system is capable and able of. While explicitly assigned or stated preservation levels are promises to adhere to a certain set of policies and decisions, it may be hard to impossible for a best effort preservation service to fulfill these expectations. Perceived preservation levels combine different outcomes from preservation actions with preservation options and available resources to convey a holistic view of the archive's worflow and decision states. A preservation system providing information about current states of digital objects puts the data producers in a position to reassure themselves of the trustworthiness of the archive without the need of formal certification. This openness has implications not only for the trust relationship between producer and archive but provides the opportunity to constantly reassess the archive's decisions and priorities from the outside.}, language = {en} } @article{ChraparyDalitzSperber2017, author = {Chrapary, Hagen and Dalitz, Wolfgang and Sperber, Wolfram}, title = {swMATH - Challenges, Next Steps, and Outlook}, volume = {Vol-1785}, journal = {CICM-WS-WIP 2016, Workshop and Work in Progress Papers at CICM 2016}, url = {http://nbn-resolving.de/urn:nbn:de:0074-1785-8}, pages = {107 -- 116}, year = {2017}, abstract = {swMATH is currently one of the most comprehensive specialized information services and search engines for Mathematical SoftWare (MSW). It was the intention of the project to support the user community by providing infor- mation about MSW and searching relevant MSW. Currently swMATH lists infor- mation of more than 13,000 items and 120,000 publications which refer to MSW. Maintaining and updating of the service is mainly done automatically, the num- ber of requests is permanently increasing. This sounds like a perfect solution. But swMATH is only a first step to a powerful information system on mathematical research data. This talk addresses some open problems for the further develop- ment of the swMATH service. It is shown that some problems for swMATH lead to central questions for the information management of mathematical research data, especially for MSW. This contains an extended content analysis of MSW, versioning and citation standard of MSW, a typing of the swMATH resources and the presentation of context information and high-quality control within the swMATH service.}, language = {en} } @article{OdesskiiWolf2013, author = {Odesskii, Alexander and Wolf, Thomas}, title = {Compatible quadratic Poisson brackets related to a family of elliptic curves}, volume = {63}, journal = {Journal of Geometry and Physics}, number = {0}, issn = {0393-0440}, pages = {107 -- 117}, year = {2013}, language = {en} } @article{AncoMacNaughtonWolf2012, author = {Anco, Stephen and MacNaughton, Steven A. and Wolf, Thomas}, title = {Conservation laws and symmetries of quasilinear radial wave equations in multi-dimensions}, volume = {53}, journal = {Journal of Mathematical Physics}, number = {5}, doi = {10.1063/1.4711814}, year = {2012}, language = {en} }