@article{34912, abstract = {{Let E be an ordinary elliptic curve over a finite field and g be a positive integer. Under some technical assumptions, we give an algorithm to span the isomorphism classes of principally polarized abelian varieties in the isogeny class of E⁹ . The varieties are first described as hermitian lattices over (not necessarily maximal) quadratic orders and then geometrically in terms of their algebraic theta null point. We also show how to algebraically compute Siegel modular forms of even weight given as polynomials in the theta constants by a careful choice of an affine lift of the theta null point. We then use these results to give an algebraic computation of Serre’s obstruction for principally polarized abelian threefolds isogenous to E³ and of the Igusa modular form in dimension 4. We illustrate our algorithms with examples of curves with many rational points over finite fields. }}, author = {{Kirschmer, Markus and Narbonne, Fabien and Ritzenthaler, Christophe and Robert, Damien}}, issn = {{0025-5718}}, journal = {{Mathematics of Computation}}, keywords = {{Applied Mathematics, Computational Mathematics, Algebra and Number Theory}}, number = {{333}}, pages = {{401--449}}, publisher = {{American Mathematical Society (AMS)}}, title = {{{Spanning the isogeny class of a power of an elliptic curve}}}, doi = {{10.1090/mcom/3672}}, volume = {{91}}, year = {{2021}}, } @article{46135, author = {{Schall, Johannes and Deconinck, Marielle and Bart, Nikolai and Florian, Matthias and Helversen, Martin and Dangel, Christian and Schmidt, Ronny and Bremer, Lucas and Bopp, Frederik and Hüllen, Isabell and Gies, Christopher and Reuter, Dirk and Wieck, Andreas D. and Rodt, Sven and Finley, Jonathan J. and Jahnke, Frank and Ludwig, Arne and Reitzenstein, Stephan}}, issn = {{2511-9044}}, journal = {{Advanced Quantum Technologies}}, keywords = {{Electrical and Electronic Engineering, Computational Theory and Mathematics, Condensed Matter Physics, Mathematical Physics, Nuclear and High Energy Physics, Electronic, Optical and Magnetic Materials, Statistical and Nonlinear Physics}}, number = {{6}}, publisher = {{Wiley}}, title = {{{Bright Electrically Controllable Quantum‐Dot‐Molecule Devices Fabricated by In Situ Electron‐Beam Lithography}}}, doi = {{10.1002/qute.202100002}}, volume = {{4}}, year = {{2021}}, } @inbook{57884, abstract = {{Although music apps are becoming increasingly popular, there has been little research on informal music practices with apps. This article presents findings of an ongoing study on learning processes and aesthetic experiences with informal appmusic practices. In particular, it discusses the aesthetic practices (Reckwitz, 2008b) of using specific places for making music. In our grounded theory study (Charmaz, 2014) we collected data using interviews, participant observation and videography. As exemplary cases, this article presents two analyses of the use of ‘inspiring places’ and ‘safe places’. The results suggest that perceiving the atmosphere is a fundamental prerequisite for both places. Additionally, the results shed light on aesthetic aspects of mobile music making. (DIPF/Orig.)}}, author = {{Eusterbrock, Linus and Godau, Marc and Haenisch, Matthias and Krebs, Matthias and Rolle, Christian}}, booktitle = {{Musikpädagogik im Spannungsfeld von Reflexion und Intervention}}, editor = {{Hasselhorn, Johannes and Kautny, Oliver and Platz, Friedrich}}, keywords = {{Education, Ästhetik, Schul- und Bildungswesen, Informal learning, Informelles Lernen, Musical education, Musikpädagogik, Anwendung, Ästhetische Erfahrung, Grounded Theory, Längsschnittuntersuchung, Learning process, Lernprozess, Longitudinal analysis, Longitudinal study, Mobiles Gerät, Music reading, Musizieren, Erziehung}}, pages = {{155–172}}, publisher = {{Waxmann}}, title = {{{Von ’inspirierenden Orten’ und ’Safe Places’. Die ästhetische Nutzung von Orten in der Appmusikpraxis}}}, volume = {{41}}, year = {{2021}}, } @article{19823, abstract = {{Individual grains of chalcopyrite solar cell absorbers can facet in different crystallographic directions at their surfaces. To gain a deeper understanding of the junction formation in these devices, we correlate variations in the surface facet orientation with the defect electronic properties. We use a combined analytical approach based on scanning tunneling spectroscopy (STS), scanning electron microscopy, and electron back scatter diffraction (EBSD), where we perform these experiments on identical surface areas as small as 2 × 2 µm2 with a lateral resolution well below 50 nm. The topography of the absorber surfaces indicates two main morphological features: micro-faceted, long basalt-like columns and their short nano-faceted terminations. Our STS results reveal that the long columns exhibit spectral signatures typical for the presence of pronounced oxidation-induced surface dipoles in conjunction with an increased density of electronic defect levels. In contrast, the nano-faceted terminations of the basalt-like columns are largely passivated in terms of electronic defect levels within the band gap region. Corresponding crystallographic data based on EBSD experiments show that the surface of the basalt-like columns can be assigned to intrinsically polar facet orientations, while the passivated terminations are assigned to non-polar planes. Ab-initio calculations suggest that the polar surfaces are more prone to oxidation and resulting O-induced defects, in comparison to non-polar planes. Our results emphasize the correlation between morphology, surface facet orientations and surface electronic properties. Furthermore, this work aids in gaining a fundamental understanding of oxidation induced lateral inhomogeneities in view of the p-n junction formation in chalcopyrite thin-film solar cells.}}, author = {{Elizabeth, Amala and Conradi, Hauke and K. Sahoo, Sudhir and Kodalle, Tim and A. Kaufmann, Christian and Kühne, Thomas and Mirhosseini, Hossein and Abou-Ras, Daniel and Mönig, Harry}}, issn = {{1359-6454}}, journal = {{Acta Materialia}}, keywords = {{Chalcopyrite absorber, Scanning tunneling spectroscopy, Electron backscatter diffraction, Density functional theory, Surface dipole}}, title = {{{Correlating facet orientation, defect-level density and dipole layer formation at the surface of polycrystalline CuInSe2 thin films}}}, doi = {{https://doi.org/10.1016/j.actamat.2020.09.028}}, volume = {{200}}, year = {{2020}}, } @inproceedings{17055, abstract = {{Understanding a new literature corpus can be a grueling experience for junior scholars. Nevertheless, corresponding guidelines have not been updated for decades. We contend that the traditional strategy of skimming all papers and reading selected papers afterwards needs to be revised. Therefore, we design a new strategy that guides the overall exploratory process by prioritizing influential papers for initial reading, followed by skimming the remaining papers. Consistent with schemata theory, starting with in-depth reading allows readers to acquire more substantial prior content schemata, which are representa-tive for the literature corpus and useful in the following skimming process. To this end, we develop a prototype that identifies the influential papers from a set of PDFs, which is illustrated in a case study in the IT business value domain. With the new strategy, we envision a more efficient process of exploring unknown literature corpora.}}, author = {{Wagner, Gerit and Empl, Philipp and Schryen, Guido}}, booktitle = {{28th European Conference on Information Systems (ECIS 2020)}}, keywords = {{Reading and skimming, Exploring literature, Review methodology, Design science research, Schemata theory}}, location = {{Marrakesh, Morocco}}, title = {{{Designing a Novel Strategy for Exploring Literature Corpora}}}, year = {{2020}}, } @article{33262, abstract = {{The authors of Berg et al. [J. Algebra 348 (2011) 446–461] provide an algorithm for finding a complete system of primitive orthogonal idempotents for CM, where M is any finite R-trivial monoid. Their method relies on a technical result stating that R-trivial monoid are equivalent to so-called weakly ordered monoids. We provide an alternative algorithm, based only on the simple observation that an R-trivial monoid may be realized by upper triangular matrices. This approach is inspired by results in the field of coupled cell network dynamical systems, where L-trivial monoids (the opposite notion) correspond to so-called feed-forward networks. We first show that our algorithm works for ZM, after which we prove that it also works for RM where R is an arbitrary ring with a known complete system of primitive orthogonal idempotents. In particular, our algorithm works if R is any field. In this respect our result constitutes a considerable generalization of the results in Berg et al. [J. Algebra 348 (2011) 446–461]. Moreover, the system of idempotents for RM is obtained from the one our algorithm yields for ZM in a straightforward manner. In other words, for any finite R-trivial monoid M our algorithm only has to be performed for ZM, after which a system of idempotents follows for any ring with a given system of idempotents.}}, author = {{Nijholt, Eddie and Rink, Bob and Schwenker, Sören}}, issn = {{0219-4988}}, journal = {{Journal of Algebra and Its Applications}}, keywords = {{Applied Mathematics, Algebra and Number Theory}}, number = {{12}}, publisher = {{World Scientific Pub Co Pte Ltd}}, title = {{{A new algorithm for computing idempotents of ℛ-trivial monoids}}}, doi = {{10.1142/s0219498821502273}}, volume = {{20}}, year = {{2020}}, } @article{35299, abstract = {{Der Artikel beschreibt unter Berücksichtigung von fachdi-daktischen Überlegungen (Religionsdidaktik und Didaktik des Schulfaches Erziehungswissenschaft, letztere wird oftmals auch als Didaktik des Unterrichtsfaches Pädagogik bezeichnet), wie durch die Thematisierung studentischer Erfahrungen in Praxisphasen begleitenden Veranstaltungen ein Beitrag zur Professionalisierung angehender Lehrkräfte geleistet werden könnte. Exemplarisch werden Vorgehensweisen aufgezeigt, wie Unterrichtserfahrungen angehender Lehrkräfte in solchen Unterrichtsfächern, die sich in Bezug auf Inhalte und Gegenstände des Unterrichts durch ein hohes Maß an Uneindeutigkeit auszeichnen, im Rahmen der universitären Veranstaltungen thematisiert und zu Theorien in Beziehung gesetzt werden können. Der Begriff Uneindeutigkeit bezeichnet dabei das Spezifikum beider Fächer, dass Fragen thematisiert und Aufgaben bearbeitet werden, die sich nicht immer eindeutig beantworten oder als richtig oder falsch bewerten lassen. Ziel der Einbindung studentischer Praxiserfahrungen und von deren Reflexion ist es, dass angehende Lehrkräfte professionelle Kompetenz entwickeln sowie für die Komplexität und Uneindeutigkeit theologischer Rede bzw. theologischen und pädagogischen Handelns und Wirkens sensibilisiert werden und gleichzeitig erkunden, wie sie Kinder und Jugendlichen in der Schule einen verlässlichen Referenzrahmen für die Entwicklung einer reflektierten religiösen bzw.pädagogischen Kompetenz vermitteln können}}, author = {{Caruso, Carina and Martin, Alexander and Woppowa, Jan}}, issn = {{2625-0675}}, journal = {{Herausforderung Lehrer*innenbildung - Zeitschrift Zur Konzeption, Gestaltung Und Diskussion}}, keywords = {{Expertise, Schulpraktikum, Praxissemester, Theorie-Praxis-Verzahnung, Uneindeutigkeit im Unterricht / ambiguity, theory-practicerelation, expertise, internships}}, number = {{2}}, pages = {{60--74}}, title = {{{Auf dem Weg zum Lehrberuf}}}, doi = {{10.4119/hlz-2500}}, volume = {{3}}, year = {{2020}}, } @article{34830, author = {{Hanusch, Maximilian}}, journal = {{Journal of Lie Theory}}, keywords = {{Lie theory, strong Trotter property}}, number = {{1}}, pages = {{025--032}}, publisher = {{Heldermann Verlag}}, title = {{{The Strong Trotter Property for Locally μ-convex Lie Groups}}}, volume = {{30}}, year = {{2020}}, } @inproceedings{48847, abstract = {{Dynamic optimization problems have gained significant attention in evolutionary computation as evolutionary algorithms (EAs) can easily adapt to changing environments. We show that EAs can solve the graph coloring problem for bipartite graphs more efficiently by using dynamic optimization. In our approach the graph instance is given incrementally such that the EA can reoptimize its coloring when a new edge introduces a conflict. We show that, when edges are inserted in a way that preserves graph connectivity, Randomized Local Search (RLS) efficiently finds a proper 2-coloring for all bipartite graphs. This includes graphs for which RLS and other EAs need exponential expected time in a static optimization scenario. We investigate different ways of building up the graph by popular graph traversals such as breadth-first-search and depth-first-search and analyse the resulting runtime behavior. We further show that offspring populations (e. g. a (1 + {$\lambda$}) RLS) lead to an exponential speedup in {$\lambda$}. Finally, an island model using 3 islands succeeds in an optimal time of {$\Theta$}(m) on every m-edge bipartite graph, outperforming offspring populations. This is the first example where an island model guarantees a speedup that is not bounded in the number of islands.}}, author = {{Bossek, Jakob and Neumann, Frank and Peng, Pan and Sudholt, Dirk}}, booktitle = {{Proceedings of the Genetic and Evolutionary Computation Conference}}, isbn = {{978-1-4503-7128-5}}, keywords = {{dynamic optimization, evolutionary algorithms, running time analysis, theory}}, pages = {{1277–1285}}, publisher = {{Association for Computing Machinery}}, title = {{{More Effective Randomized Search Heuristics for Graph Coloring through Dynamic Optimization}}}, doi = {{10.1145/3377930.3390174}}, year = {{2020}}, } @inproceedings{48851, abstract = {{Several important optimization problems in the area of vehicle routing can be seen as variants of the classical Traveling Salesperson Problem (TSP). In the area of evolutionary computation, the Traveling Thief Problem (TTP) has gained increasing interest over the last 5 years. In this paper, we investigate the effect of weights on such problems, in the sense that the cost of traveling increases with respect to the weights of nodes already visited during a tour. This provides abstractions of important TSP variants such as the Traveling Thief Problem and time dependent TSP variants, and allows to study precisely the increase in difficulty caused by weight dependence. We provide a 3.59-approximation for this weight dependent version of TSP with metric distances and bounded positive weights. Furthermore, we conduct experimental investigations for simple randomized local search with classical mutation operators and two variants of the state-of-the-art evolutionary algorithm EAX adapted to the weighted TSP. Our results show the impact of the node weights on the position of the nodes in the resulting tour.}}, author = {{Bossek, Jakob and Casel, Katrin and Kerschke, Pascal and Neumann, Frank}}, booktitle = {{Proceedings of the Genetic and Evolutionary Computation Conference}}, isbn = {{978-1-4503-7128-5}}, keywords = {{dynamic optimization, evolutionary algorithms, running time analysis, theory}}, pages = {{1286–1294}}, publisher = {{Association for Computing Machinery}}, title = {{{The Node Weight Dependent Traveling Salesperson Problem: Approximation Algorithms and Randomized Search Heuristics}}}, doi = {{10.1145/3377930.3390243}}, year = {{2020}}, } @article{45955, author = {{Akrivis, Georgios and Feischl, Michael and Kovács, Balázs and Lubich, Christian}}, issn = {{0025-5718}}, journal = {{Mathematics of Computation}}, keywords = {{Applied Mathematics, Computational Mathematics, Algebra and Number Theory}}, number = {{329}}, pages = {{995--1038}}, publisher = {{American Mathematical Society (AMS)}}, title = {{{Higher-order linearly implicit full discretization of the Landau–Lifshitz–Gilbert equation}}}, doi = {{10.1090/mcom/3597}}, volume = {{90}}, year = {{2020}}, } @article{34842, abstract = {{Let D<0 be a fundamental discriminant and denote by E(D) the exponent of the ideal class group Cl(D) of K=ℚ(√D). Under the assumption that no Siegel zeros exist we compute all such D with E(D) dividing 8. We compute all D with |D| ≤ 3.1⋅10²⁰ such that E(D) ≤ 8.}}, author = {{Elsenhans, Andreas-Stephan and Klüners, Jürgen and Nicolae, Florin}}, issn = {{0065-1036}}, journal = {{Acta Arithmetica}}, keywords = {{Algebra and Number Theory}}, number = {{3}}, pages = {{217--233}}, publisher = {{Institute of Mathematics, Polish Academy of Sciences}}, title = {{{Imaginary quadratic number fields with class groups of small exponent}}}, doi = {{10.4064/aa180220-20-3}}, volume = {{193}}, year = {{2020}}, } @inbook{35811, author = {{Biehler, Rolf and Durand-Guerrier, Viviane}}, booktitle = {{Proceedings of the Third Conference of the International Network for Didactic Research in University Mathematics (INDRUM 2020, 12-19 September 2020)}}, editor = {{Hausberger, T. and Bosch, M. and Chelloughi, F.}}, keywords = {{Number Theory, Algebra, Discrete Mathematics, Logic, Research in University Mathematics Edcuation}}, pages = {{283--287}}, publisher = {{University of Carthage and INDRUM}}, title = {{{University Mathematics Didactic Research on Number Theory, Algebra, Discrete Mathematics, Logic}}}, year = {{2020}}, } @article{34841, abstract = {{We give an exact formula for the number of G-extensions of local function fields Fq((t)) for finite abelian groups G up to a conductor bound. As an application we give a lower bound for the corresponding counting problem by discriminant. }}, author = {{Klüners, Jürgen and Müller, Raphael}}, issn = {{0022-314X}}, journal = {{Journal of Number Theory}}, keywords = {{Algebra and Number Theory}}, pages = {{311--322}}, publisher = {{Elsevier BV}}, title = {{{The conductor density of local function fields with abelian Galois group}}}, doi = {{10.1016/j.jnt.2019.11.007}}, volume = {{212}}, year = {{2020}}, } @inproceedings{9676, abstract = {{Employees’ acceptance and resistance of new technology and social structure are frequently examined in Information Systems research. Resistance is expressed in various forms, including a lack of cooperation, workarounds, and physical sabotage. Workarounds, in particular, have a dual nature and can refer to both, undesirable behavior that contradicts organizational struc-ture and to desired organizational innovation. While antecedents and different forms of worka-rounds have been explored, literature has remained silent on how and why workarounds of an individual employee can affect activities performed by other employees and thereby, change work routines on an organizational level. Since employees’ day-to-day performances constitute the ostensive patterns of a routine, we argue that workarounds will not only impact performanc-es of adjacent routines, but also transform the organization as a social structure. With a prelim-inary set of qualitative data from 24 interviews, we used a multiple case study design to concep-tualize six patterns that illustrate how and why workarounds can spread through an organiza-tion. The patterns are systematized by a framework that considers three types of collaboration and two types of handoffs across routines. This first evidence points at the nature of complex desired and undesired consequences that can emerge through workarounds performed in an organization.}}, author = {{Wolf, Verena and Beverungen, Daniel}}, booktitle = {{Proceedings of the 27th European Conference on Information Systems (ECIS)}}, keywords = {{Resistance, Workaround, Organizational Routines, Structuration Theory}}, location = {{Stockholm-Uppsala, Sweden}}, title = {{{Conceptualizing the Impact of Workarounds – An Organizational Routines’ Perspective}}}, year = {{2019}}, } @article{13225, abstract = {{Abstract The effect of extending the O−H bond length(s) in water on the hydrogen-bonding strength has been investigated using static ab initio molecular orbital calculations. The “polar flattening” effect that causes a slight σ-hole to form on hydrogen atoms is strengthened when the bond is stretched, so that the σ-hole becomes more positive and hydrogen bonding stronger. In opposition to this electronic effect, path-integral ab initio molecular-dynamics simulations show that the nuclear quantum effect weakens the hydrogen bond in the water dimer. Thus, static electronic effects strengthen the hydrogen bond in H2O relative to D2O, whereas nuclear quantum effects weaken it. These quantum fluctuations are stronger for the water dimer than in bulk water.}}, author = {{Clark, Timothy and Heske, Julian Joachim and Kühne, Thomas}}, journal = {{ChemPhysChem}}, keywords = {{ab initio calculations, bond theory, hydrogen bonds, isotope effects, solvent effects}}, pages = {{1--6}}, title = {{{Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H2O and D2O}}}, doi = {{10.1002/cphc.201900839}}, volume = {{20}}, year = {{2019}}, } @techreport{10332, abstract = {{We analyze the incentives for retail bundling and the welfare effects of retail bundling in a decentralized distribution channel with two retailers and two monopolistic manufacturers. One manufacturer exclusively sells his good to one retailer, whereas the other manufacturer sells his good to both retailers. Thus, one retailer is a monopolist for one product but competes with the other retailer in the second product market. The two-product retailer has the option to bundle his goods or to sell them separately. We find that bundling aggravates the double marginalization problem for the bundling retailer. Nevertheless, when the retailers compete in prices, bundling can be more profitable than separate selling for the retailer as bundling softens the retail competition. The ultimate outcome depends on the manufacturers’ marginal costs. Given retail quantity competition, however, bundling is in no case the retailer’s best strategy. Furthermore, we show that profitable bundling reduces consumer and producer surplus in the equilibrium.}}, author = {{Heinzel, Joachim Maria Josef}}, keywords = {{retail bundling, leverage theory, double marginalization}}, publisher = {{CIE Working Paper Series}}, title = {{{Bundling in a Distribution Channel with Retail Competition}}}, year = {{2019}}, } @article{34917, abstract = {{We relate proper isometry classes of maximal lattices in a totally definite quaternary quadratic space (V,q) with trivial discriminant to certain equivalence classes of ideals in the quaternion algebra representing the Clifford invariant of (V,q). This yields a good algorithm to enumerate a system of representatives of proper isometry classes of lattices in genera of maximal lattices in (V,q).}}, author = {{Kirschmer, Markus and Nebe, Gabriele}}, issn = {{1793-0421}}, journal = {{International Journal of Number Theory}}, keywords = {{Algebra and Number Theory}}, number = {{02}}, pages = {{309--325}}, publisher = {{World Scientific Pub Co Pte Lt}}, title = {{{Quaternary quadratic lattices over number fields}}}, doi = {{10.1142/s1793042119500131}}, volume = {{15}}, year = {{2019}}, } @article{34916, abstract = {{We describe the powers of irreducible polynomials occurring as characteristic polynomials of automorphisms of even unimodular lattices over number fields. This generalizes results of Gross & McMullen and Bayer-Fluckiger & Taelman.}}, author = {{Kirschmer, Markus}}, issn = {{0022-314X}}, journal = {{Journal of Number Theory}}, keywords = {{Algebra and Number Theory}}, pages = {{121--134}}, publisher = {{Elsevier BV}}, title = {{{Automorphisms of even unimodular lattices over number fields}}}, doi = {{10.1016/j.jnt.2018.08.004}}, volume = {{197}}, year = {{2019}}, } @inproceedings{48843, abstract = {{We contribute to the theoretical understanding of randomized search heuristics for dynamic problems. We consider the classical graph coloring problem and investigate the dynamic setting where edges are added to the current graph. We then analyze the expected time for randomized search heuristics to recompute high quality solutions. This includes the (1+1) EA and RLS in a setting where the number of colors is bounded and we are minimizing the number of conflicts as well as iterated local search algorithms that use an unbounded color palette and aim to use the smallest colors and - as a consequence - the smallest number of colors. We identify classes of bipartite graphs where reoptimization is as hard as or even harder than optimization from scratch, i. e. starting with a random initialization. Even adding a single edge can lead to hard symmetry problems. However, graph classes that are hard for one algorithm turn out to be easy for others. In most cases our bounds show that reoptimization is faster than optimizing from scratch. Furthermore, we show how to speed up computations by using problem specific operators concentrating on parts of the graph where changes have occurred.}}, author = {{Bossek, Jakob and Neumann, Frank and Peng, Pan and Sudholt, Dirk}}, booktitle = {{Proceedings of the Genetic and Evolutionary Computation Conference}}, isbn = {{978-1-4503-6111-8}}, keywords = {{dynamic optimization, evolutionary algorithms, running time analysis, theory}}, pages = {{1443–1451}}, publisher = {{Association for Computing Machinery}}, title = {{{Runtime Analysis of Randomized Search Heuristics for Dynamic Graph Coloring}}}, doi = {{10.1145/3321707.3321792}}, year = {{2019}}, }