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Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
• 301.
On the group algebra decomposition of a Jacobian variety2016Inngår i: REVISTA DE LA REAL ACADEMIA DE CIENCIAS EXACTAS FISICAS Y NATURALES SERIE A-MATEMATICAS, ISSN 1578-7303, Vol. 110, nr 1, s. 185-199Artikkel i tidsskrift (Fagfellevurdert)

Given a compact Riemann surface X with an action of a finite group G, the group algebra provides an isogenous decomposition of its Jacobian variety JX, known as the group algebra decomposition of JX. We obtain a method to concretely build a decomposition of this kind. Our method allows us to study the geometry of the decomposition. For instance, we build several decompositions in order to determine which one has kernel of smallest order. We apply this method to families of trigonal curves up to genus 10.

• 302.
Linköpings universitet, Institutionen för beteendevetenskap och lärande.
Linköpings universitet, Institutionen för beteendevetenskap och lärande.
Olika aspekter av bråk: En litteraturstudie om elevers svårigheter och hur lärare kan underlätta elevers förståelse för bråk i årskurs 4-6.2017Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave

Syftet med denna litteraturstudie var att granska och analysera vad forskning visar beträffande elevers svårigheter för området bråk, samt hur lärare kan underlätta elevers förståelse för bråk i årskurs 4-6. I litteraturstudien har databassökningar gjorts via UniSearch, ERIC, MathEduc och Google Scholar. Även manuella sökningar har använts. Bråk tonas ned i dagens undervisning och resultat från TIMSS och PISA visar att bråk är ett, för elever såväl som lärare, problematiskt område i matematiken. Forskare framhåller bland annat elevers svårigheter för täljaren och nämnarens innebörd, samt jämförelse och beräkning av bråkuttryck. Vidare framhäver forskare att lärare med bland annat diskussioner i klassrummet, praktiskt material, samt en verklighetsanknuten och elevcentrerad bråkundervisning främjar elevers inlärning. Resultaten visar dock att forskare inte är eniga vad gäller de svårigheter elever har på området bråk.

• 303.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Vad kom först – matrisen eller determinanten?: Om axiomatiseringen av den linjära algebran2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
• 304.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra, geometri och logik.
Asymptotiska egenskaper hos vissa kombinatoriska strukturer2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
• 305.
Högskolan i Jönköping, Högskolan för lärande och kommunikation, HLK, Skolnära forskning, Matematikdidaktik.
Högskolan i Jönköping, Högskolan för lärande och kommunikation, HLK, Skolnära forskning, Matematikdidaktik.
Structure sense: Ett matematikdidaktiskt begrepp som håller på att formas2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave

Structure sense är ett begrepp som nyligen har börjat användas inom matematikdidaktik föratt beskriva elevers förståelse för matematiska strukturer. Syftet med det härexamensarbetet är att utforska begreppet structure sense genom att jämföra olikadefinitioner av begreppet. Vidare är syftet också att jämföra structure sense med tre andraliknande begrepp: symbol sense, personal structure och awareness of mathematical pattern and structure. Litteraturstudien bygger på 13 vetenskapliga publikationer som samlades in ochanalyserades. Samtliga publikationer är skrivna av internationella forskare. I resultatetpresenteras och jämförs structure sense utifrån fyra olika definitioner. De olikadefinitionerna av begreppet är riktade mot olika nivåer av matematik men gemensamt förbeskrivningarna är att structure sense uppfattas som en eller flera förmågor som innefattarett mångfacetterat sätt att uppfatta matematisk struktur.

• 306.
Friedrich-Schiller-Univesität, JGermany.
Computation of Poincare-Betti series for monomial rings2005Inngår i: Rendiconti dell'Istituto di Matematica dell'Università di Trieste, ISSN 0049-4704, E-ISSN 2464-8728, Vol. 37, nr 1-2, s. 85-94Artikkel i tidsskrift (Fagfellevurdert)
• 307.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Uncountable categoricity2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
• 308.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Bimodules over dual numbers2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
• 309.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Ordnade kroppar och Artin-Schreiers teorem2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
• 310.
School of Philosophy, Beijing Normal University.
Institute for Logic, Language and Computation, University of Amsterdam.
A logic for temporal conditionals and a solution to the Sea Battle Puzzle2018Inngår i: Proceedings of the 12th International Conference on Advances in Modal Logic (AiML'2018), London, 2018, s. 379---398Konferansepaper (Fagfellevurdert)

Temporal reasoning with conditionals is more complex than both classical temporal reasoning and reasoning with timeless conditionals, and can lead to some rather counter-intuitive conclusions. For instance, Aristotle’s famous “Sea Battle Tomorrow” puzzle leads to a fatalistic conclusion: whether there will be a sea battle tomorrow or not, but that is necessarily the case now. We propose a branching-time logic LTC to formalise reasoning about temporal conditionals and provide that logic with adequate formal semantics. The logic LTC extends the Nexttime fragment of CTL∗ , with operators for model updates, restricting the domain to only future moments where antecedent is still possible to satisfy. We provide formal semantics for these operators that implements the restrictor interpretation of antecedents of temporalized conditionals, by suitably restricting the domain of discourse. As a motivating example, we demonstrate that a naturally formalised in our logic version of the ‘Sea Battle’ argument renders it unsound, thereby providing a solution to the problem with fatalist conclusion that it entails, because its underlying reasoning per cases argument no longer applies when these cases are treated not as material implications but as temporal conditionals. On the technical side, we analyze the semantics of LTC and provide a series of reductions of LTC-formulae, first recursively eliminating the dynamic update operators and then the path quantifiers in such formulae. Using these reductions we obtain a sound and complete axiomatization for LTC, and reduce its decision problem to that of the modal logic KD.

• 311. Ju, Fengkui
Stockholms universitet, Humanistiska fakulteten, Filosofiska institutionen. University of Johannesburg, South Africa.
A logic for temporal conditionals and a solution to the Sea Battle Puzzle2018Inngår i: Advances in Modal Logic / [ed] Guram Bezhanishvili, Giovanna D'Agostino, George Metcalfe, Thomas Studer, London: College Publications, 2018, s. 379-398Konferansepaper (Fagfellevurdert)

Temporal reasoning with conditionals is more complex than both classical temporal reasoning and reasoning with timeless conditionals, and can lead to some rather counter-intuitive conclusions. For instance, Aristotle’s famous “Sea Battle Tomorrow” puzzle leads to a fatalistic conclusion: whether there will be a sea battle tomorrow or not, but that is necessarily the case now. We propose a branching-time logic LTC to formalise reasoning about temporal conditionals and provide that logic with adequate formal semantics. The logic LTC extends the Nexttime fragment of CTL∗ , with operators for model updates, restricting the domain to only future moments where antecedent is still possible to satisfy. We provide formal semantics for these operators that implements the restrictor interpretation of antecedents of temporalized conditionals, by suitably restricting the domain of discourse. As a motivating example, we demonstrate that a naturally formalised in our logic version of the ‘Sea Battle’ argument renders it unsound, thereby providing a solution to the problem with fatalist conclusion that it entails, because its underlying reasoning per cases argument no longer applies when these cases are treated not as material implications but as temporal conditionals. On the technical side, we analyze the semantics of LTC and provide a series of reductions of LTC-formulae, first recursively eliminating the dynamic update operators and then the path quantifiers in such formulae. Using these reductions we obtain a sound and complete axiomatization for LTC, and reduce its decision problem to that of the modal logic KD.

• 312.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
The complete parsimony haplotype inference problem and algorithms based on integer programming, branch-and-bound and Boolean satisfiability2016Inngår i: Journal of Discrete Algorithms, ISSN 1570-8667, E-ISSN 1570-8675, Vol. 37, s. 68-83Artikkel i tidsskrift (Fagfellevurdert)

Haplotype inference by pure parsimony (HIPP) is a well-known paradigm for haplotype inference. In order to assess the biological significance of this paradigm, we generalize the problem of HIPP to the problem of finding all optimal solutions, which we call CHIPP. We study intrinsic haplotype features, such as backbone haplotypes and fat genotypesas well as equal columns and decomposability. We explicitly exploit these features in three computational approaches that are based on integer linear programming, depth-first branch-and-bound, and Boolean satisfiability. Further we introduce two hybrid algorithms that draw upon the diverse strengths of the approaches. Our experimental analysis shows that our optimized algorithms are significantly superior to the baseline algorithms, often with orders of magnitude faster running time. Finally, our experiments provide some useful insights into the intrinsic features of this important problem.

• 313.
University of Western Ontario.
Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
The homotopy theory of type theoriesManuskript (preprint) (Annet vitenskapelig)

We construct a left semi-model structure on the category of intensional type theories (precisely, on CxlCat_{Id,1,Σ(,Πext)}). This presents an infinity-category of such type theories; we show moreover that there is an infinity-functor Cl_∞ from there to the infinity-category of suitably structured quasi-categories. This allows a precise formulation of the conjectures that intensional type theory gives internal languages for higher categories, and provides a framework and toolbox for further progress on these conjectures.

• 314. Katzman, Mordechai
University of Michigan, USA.
D-module and F-module length of local cohomology modules2018Inngår i: Transactions of the American Mathematical Society, ISSN 0002-9947, E-ISSN 1088-6850, Vol. 370, nr 12, s. 8551-8580Artikkel i tidsskrift (Fagfellevurdert)

Let R be a polynomial or power series ring over a field k. We study the length of local cohomology modules H-I(j) (R) in the category of D-modules and F-modules. We show that the D-module length of H-I(j) (R) is bounded by a polynomial in the degree of the generators of I. In characteristic p > 0 we obtain upper and lower bounds on the F-module length in terms of the dimensions of Frobenius stable parts and the number of special primes of local cohomology modules of R/I. The obtained upper bound is sharp if R/I is an isolated singularity, and the lower bound is sharp when R/I is Gorenstein and F-pure. We also give an example of a local cohomology module that has different D-module and F-module lengths.

• 315.
Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
Cognitive processes of the brain: An ultrametric model of information dynamics in unconsciousness2014Inngår i: P-Adic Numbers, Ultrametric Analysis, and Applications, ISSN 2070-0466, E-ISSN 2070-0474, Vol. 6, nr 4, s. 293-302Artikkel i tidsskrift (Fagfellevurdert)

We discuss differences in mathematical representations of the physical and mentalworlds. Following Aristotle, we present the mental space as discrete, hierarchic, and totally disconnectedtopological space. One of the basic models of such spaces is given by ultrametricspaces and more specially by m-adic trees. We use dynamical systems in such spaces to modelflows of unconscious information at different level of mental representation hierarchy, for “mentalpoints”, categories, and ideas. Our model can be interpreted as an unconventional computationalmodel: non-algorithmic hierarchic “computations” (identified with the process of thinking at theunconscious level).

• 316.
Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
Foundations of analysis on superspace — 1: Differential calculus2015Inngår i: P-Adic Numbers, Ultrametric Analysis, and Applications, ISSN 2070-0466, E-ISSN 2070-0474, Vol. 7, nr 2, s. 96-110Artikkel i tidsskrift (Fagfellevurdert)

The recent experimental confirmation of the existence of Higgs boson stimulates theoretical research on supersymmetric models; in particular, mathematics of such modeling. Therefore we plan to present essentials of one special approach to “super-mathematics”, so called functional superanalysis (in the spirit of De Witt, Rogers, Vladimirov and Volovich, and the author of this review) in compact and clear form in series of review-type papers. This first paper is a review on super-differential calculus for the concrete model of the superspace (invented by Vladimirov and Volovich). In the next review we plan to present the integral supercalculus. The main distinguishing feature of functional superanalysis is that this is a real super-extension of analysis of Newton and Leibniz, opposite to algebraic models of Martin and Berezin. Here functions of commuting and anticommuting variables are no simply algebraic elements belonging to Grassmann algebras, but point-wise maps, from superspace into superspace. Finally, we remark that the first non-Archimedean physical model was based on invention by Vladimirov and Volovich of superspaces based on supercommutative Banach superalgebras over non-Archimedean (in particular, p-adic) fields. This model plays the basic role in theory of p-adic superstrings.

• 317.
Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Matematiska och systemtekniska institutionen. Matematik.
Logical approach to p-adic probabilities2006Inngår i: Bulletin of the Section of Logic, ISSN 0138-0680, Vol. 35/1, s. 49-57Artikkel i tidsskrift (Fagfellevurdert)

We study coupling between logic an p-adic probability

• 318.
Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
Institute of System Analysis of Russian Academy of Science, Russia.
Towards ultrametric modeling of unconscious creativity2015Inngår i: International Journal of Cognitive Informatics and Natural Intelligence, ISSN 1557-3958, E-ISSN 1557-3966, Vol. 8, nr 4, s. 98-109Artikkel i tidsskrift (Fagfellevurdert)

Information processed by complex cognitive systems is characterized by the presence of various closely connected hierarchic structures. The most natural geometry for the representation of such structures is geometry of trees and the corresponding topology is the ultrametric topology of on these trees. And the p-adic trees provide the simplest model for representation of mental hierarchies. Moreover, p-adic trees can be endowed with the natural arithmetic reminding the usual arithmetic of real numbers. Therefore it is natural to start from the p-adic models of brain's functioning. In this note the authors apply this model to demonstrate the ability of the “p-adic brain” to process adequately the objects of the physical Euclidean space in the p-adic tree representation. This study also leads to p-adic modeling of brain's creativity and its ability to create abstract images. The authors' model is about unconscious processing of information by the brain. Therefore the authors can say about elements of coming theory of unconscious creativity.

• 319.
Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
Univ. Nacional Autónoma de Mexico (UNAM), Mexico. Caracterizac Yacimientos Act Prod Maloob Zaap, Mexico.
Application of p-Adic Wavelets to Model Reaction–Diffusion Dynamics in Random Porous Media2016Inngår i: Journal of Fourier Analysis and Applications, ISSN 1069-5869, E-ISSN 1531-5851, Vol. 22, nr 4, s. 809-822Artikkel i tidsskrift (Fagfellevurdert)

Fourier and more generally wavelet analysis over the fields of p-adic numbers are widely used in physics, biology and cognitive science, and recently in geophysics. In this note we present a model of the reaction–diffusion dynamics in random porous media, e.g., flow of fluid (oil, water or emulsion) in a a complex network of pores with known topology. Anomalous diffusion in the model is represented by the system of two equations of reaction–diffusion type, for the part of fluid not bound to solid’s interface (e.g., free oil) and for the part bound to solid’s interface (e.g., solids–bound oil). Our model is based on the p-adic (treelike) representation of pore-networks. We present the system of two p-adic reaction–diffusion equations describing propagation of fluid in networks of pores in random media and find its stationary solutions by using theory of p-adic wavelets. The use of p-adic wavelets (generalizing classical wavelet theory) gives a possibility to find the stationary solution in the analytic form which is typically impossible for anomalous diffusion in the standard representation based on the real numbers.

• 320.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Decomposition of Tensor Products Involving a Steinberg Module2017Inngår i: Algebras and Representation Theory, ISSN 1386-923X, E-ISSN 1572-9079, Vol. 20, nr 4, s. 951-975Artikkel i tidsskrift (Fagfellevurdert)

We study the decomposition of tensor products between a Steinberg module and a costandard module, both as a module for the algebraic group G and when restricted to either a Frobenius kernel G (r) or a finite Chevalley group . In all three cases, we give formulas reducing this to standard character data for G. Along the way, we use a bilinear form on the characters of finite dimensional G-modules to give formulas for the dimension of homomorphism spaces between certain G-modules when restricted to either G (r) or . Further, this form allows us to give a new proof of the reciprocity between tilting modules and simple modules for G which has slightly weaker assumptions than earlier such proofs. Finally, we prove that in a suitable formulation, this reciprocity is equivalent to Donkin's tilting conjecture.

• 321.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Special Modules Over Positively Based Algebras2016Inngår i: Documenta Mathematica, ISSN 1431-0635, E-ISSN 1431-0643, Vol. 21, s. 1171-1192Artikkel i tidsskrift (Fagfellevurdert)

We use the Perron-Frobenius Theorem to define, study and, in some sense, classify special simple modules over arbitrary finite dimensional positively based algebras. For group algebras of finite Weyl groups with respect to the Kazhdan-Lusztig basis, this agrees with Lusztig's notion of a special module introduced in [Lu2].

• 322.
Univ Haute Alsace, France.
Univ Haute Alsace, France. Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
On (n+1)-Hom-Lie algebras induced by n-Hom-Lie algebras2016Inngår i: Georgian Mathematical Journal, ISSN 1072-947X, E-ISSN 1572-9176, Vol. 23, nr 1, s. 75-95Artikkel i tidsskrift (Fagfellevurdert)

The purpose of this paper is to study the relationships between an n-Hom-Lie algebra and its induced (n + 1)-Hom-Lie algebra. We provide an overview of the theory and explore structure properties such as ideals, centers, derived series, solvability, nilpotency, central extensions, and the cohomology.

• 323.
Institute of Algebra and Number Theory, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany.
Institute of Algebra and Number Theory, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany. Mechanics and Mathematics Faculty, Kiev National University, 01033 Kiev, Ukraine.
Quasi-hereditary algebras, exact Borel subalgebras, A∞-categories and boxes2014Inngår i: Advances in Mathematics, ISSN 0001-8708, E-ISSN 1090-2082, Vol. 262, s. 546-592Artikkel i tidsskrift (Fagfellevurdert)

Highest weight categories arising in Lie theory are known to be associated with finite dimensional quasi-hereditary algebras such as Schur algebras or blocks of category O. An analogue of the PBW theorem will be shown to hold for quasi-hereditary algebras: Up to Morita equivalence each such algebra has an exact Borel subalgebra. The category F(\Delta) of modules with standard (Verma, Weyl, …) filtration, which is exact, but rarely abelian, will be shown to be equivalent to the category of representations of a directed box. This box is constructed as a quotient of a dg algebra associated with the A-infinity-structure on Ext(\Delta,\Delta). Its underlying algebra is an exact Borel subalgebra.

• 324.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Classification of Root Systems2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
• 325.
Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
My First Meetings with Konstantin Oskolkov2013Inngår i: Recent Advances in Harmonic Analysis and Applications: In honor of Konstantin Oskolkov / [ed] Dmitriy Bilyk, Laura De Carli, Alexander Petukhov, Alexander M. Stokolos, Brett D. Wick, Springer, 2013, 1, Vol. 25, s. 27-29Kapittel i bok, del av antologi (Fagfellevurdert)

This note tells about our first meetings with Konstatin Oskolkov. We discuss also optimal estimates of the rate of convergence of Fourier series obtained by Oskolkov in 1975.

• 326.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori.
A multilinear algebra proof of the Cauchy-Binet formula and a multilinear version of Parseval's identity2013Inngår i: Linear Algebra and its Applications, ISSN 0024-3795, E-ISSN 1873-1856, Vol. 439, nr 9, s. 2651-2658Artikkel i tidsskrift (Fagfellevurdert)

We prove the Cauchy-Binet determinantal formula using multilinear algebra by first generalizing it to an identity not involving determinants. By extending the formula to abstract Hilbert spaces we obtain, as a corollary, a generalization of the classical Parseval identity.

• 327.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen.
A limit law of almost l-partite graphs2013Inngår i: Journal of Symbolic Logic (JSL), ISSN 0022-4812, E-ISSN 1943-5886, Vol. 78, nr 3, s. 911-936Artikkel i tidsskrift (Fagfellevurdert)

For integers l >= 1, d >= 0 we study (undirected) graphs with vertices 1,..., n such that the vertices can be partitioned into l parts such that every vertex has at most d neighbours in its own part. The set of all such graphs is denoted P-n (l, d). We prove a labelled first-order limitlaw, i.e., for every first-order sentence phi, the proportion of graphs in P-n (l, d) that satisfy phi converges as n -> infinity. By combining this result with a result of Hundack, Promel and Steger [12] we also prove that if 1 <= s(1) <=...<= s(1) are integers, then Forb(A(I),s(1),...,s(l)) has alabelled first-order limit law, where Forb (A(I),s(1),...,s(l)) denotes the set of all graphs with vertices 1,..., n, for some n, in which there is no subgraph isomorphic to the complete (l + 1)-partite graph with parts of sizes 1, S-1,..., S-l. In the course of doing this we also prove that there exists a first-order formula depending only on l and d, such that the proportion of g e P (I, d) with the following property approaches 1 as n ->infinity: there is a unique partition of {1,..., n} into l parts such that every vertex has at most d neighbours in its own part, and this partition, viewed as an equivalence relation, is defined by xi.

• 328.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen.
Binary primitive homogeneous simple structures2017Inngår i: Journal of Symbolic Logic (JSL), ISSN 0022-4812, E-ISSN 1943-5886, Vol. 82, nr 1, s. 183-207Artikkel i tidsskrift (Fagfellevurdert)

Suppose that M is countable, binary, primitive, homogeneous, and simple. We prove that the SU-rank of the complete theory of M is 1 and hence 1-based. It follows that M is a random structure. The conclusion that M is a random structure does not hold if the binarity condition is removed, as witnessed by the generic tetrahedron-free 3-hypergraph. However, to show that the generic tetrahedron-free 3-hypergraph is 1-based requires some work (it is known that it has the other properties) since this notion is defined in terms of imaginary elements. This is partly why we also characterize equivalence relations which are definable without parameters in the context of omega-categorical structures with degenerate algebraic closure. Another reason is that such characterizations may be useful in future research about simple (nonbinary) homogeneous structures.

• 329.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Binary simple homogeneous structures are supersimple with finite rank2016Inngår i: Proceedings of the American Mathematical Society, ISSN 0002-9939, E-ISSN 1088-6826, Vol. 144, nr 4, s. 1745-1759Artikkel i tidsskrift (Fagfellevurdert)

Suppose that M is an infinite structure with finite relational vocabulary such that every relation symbol has arity at most 2. If M is simple and homogeneous, then its complete theory is supersimple with finite SU-rank which cannot exceed the number of complete 2-types over the empty set.

• 330.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen.
Homogeneous 1-based structures and interpretability in random structures2017Inngår i: Mathematical logic quarterly, ISSN 0942-5616, E-ISSN 1521-3870, Vol. 63, nr 1-2, s. 6-18Artikkel i tidsskrift (Fagfellevurdert)

Let V be a finite relational vocabulary in which no symbol has arity greater than 2. Let math formula be countable V-structure which is homogeneous, simple and 1-based. The first main result says that if math formula is, in addition, primitive, then it is strongly interpretable in a random structure. The second main result, which generalizes the first, implies (without the assumption on primitivity) that if math formula is “coordinatized” by a set with SU-rank 1 and there is no definable (without parameters) nontrivial equivalence relation on M with only finite classes, then math formula is strongly interpretable in a random structure.

• 331.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
On Constraints And Dividing In Ternary Homogeneous Structures2018Inngår i: Journal of Symbolic Logic (JSL), ISSN 0022-4812, E-ISSN 1943-5886, Vol. 83, nr 4, s. 1691-1721Artikkel i tidsskrift (Fagfellevurdert)

Let M be ternary, homogeneous and simple. We prove that if M is finitely constrained, then it is supersimple with finite SU-rank and dependence is k-trivial for some k < omega and for finite sets of real elements. Now suppose that, in addition, M is supersimple with SU-rank 1. If M is finitely constrained then algebraic closure in M is trivial. We also find connections between the nature of the constraints of M, the nature of the amalgamations allowed by the age of M, and the nature of definable equivalence relations. A key method of proof is to "extract" constraints (of M) from instances of dividing and from definable equivalence relations. Finally, we give new examples, including an uncountable family, of ternary homogeneous supersimple structures of SU-rank 1.

• 332.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Random graphs with bounded maximum degree: asymptotic structure and a logical limit law2012Inngår i: Discrete mathematics and theoretical computer science (Online), ISSN 1462-7264, E-ISSN 1365-8050, Vol. 14, nr 2, s. 229-254Artikkel i tidsskrift (Fagfellevurdert)
• 333.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Some connections between finite and infinite model theory2011Inngår i: Finite and Algorithmic Model Theory / [ed] Javier Esparza, Christian Michaux, Charles Steinhorn, Cambridge University Press, 2011, s. 109-139Kapittel i bok, del av antologi (Annet vitenskapelig)
• 334.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Typical automorphism groups of finite nonrigid structures2015Inngår i: Archive for mathematical logic, ISSN 0933-5846, E-ISSN 1432-0665, Vol. 54, nr 5-6, s. 571-586Artikkel i tidsskrift (Fagfellevurdert)
• 335.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Helsingfors Universitet.
On compactness of logics that can express properties of symmetry or connectivity2015Inngår i: Studia Logica: An International Journal for Symbolic Logic, ISSN 0039-3215, E-ISSN 1572-8730, Vol. 103, nr 1, s. 1-20Artikkel i tidsskrift (Fagfellevurdert)

A condition, in two variants, is given such that if a property P satisfies this condition, then every logic which is at least as strong as first-order logic and can express P fails to have the compactness property. The result is used to prove that for a number of natural properties P speaking about automorphism groups or connectivity, every logic which is at least as strong as first-order logic and can express P fails to have the compactness property. The basic idea underlying the results and examples presented here is that it is possible to construct a countable first-order theory T such that every model of T has a very rich automorphism group, but every finite subset T' of T has a model which is rigid.

• 336.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för matematikämnets och naturvetenskapsämnenas didaktik.
”Det blir lika med…”: En studie om hur elever i en årskurs 4 resonerar kring likhetstecknet2010Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave

I denna studie undersöktes hur några elever i en årskurs 4 resonerar kring likhetstecknet. Undersökningen gjordes med hjälp av kvalitativa intervjuer. Eleverna var valda och placerade på måfå i grupper där de sedan fick diskutera kring tre matematiska likheter.

Studien visar på tendenser av relationell förståelse för likhetstecknet hos eleverna, men samtidigt problematiseras skillnaden mellan den relationella och den operationella förståelsen. Studien kommer fram till att eleverna diskuterar om uppgiftens konstiga utformning när operationen är på högra sidan av likhetstecknet och svaret är på den vänstra sidan. Eleverna hänvisar till kutym och läroböcker. Av studien framkommer det också att eleverna jämför likheterna ofta med balansvågen, både muntligt men också kroppsligt. Studien tenderar även att ge en bild av att elevers svar skiljer sig beroende på vilka uppgifterna är.

• 337.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Homotopy equivalence of nearby Lagrangians and the Serre spectral sequence2017Inngår i: Mathematische Annalen, ISSN 0025-5831, E-ISSN 1432-1807, Vol. 368, nr 3-4, s. 945-970Artikkel i tidsskrift (Fagfellevurdert)

We construct using relatively basic techniques a spectral sequence for exact Lagrangians in cotangent bundles similar to the one constructed by Fukaya, Seidel, and Smith. That spectral sequence was used to prove that exact relative spin Lagrangians in simply connected cotangent bundles with vanishing Maslov class are homology equivalent to the base (a similar result was also obtained by Nadler). The ideas in that paper were extended by Abouzaid who proved that vanishing Maslov class alone implies homotopy equivalence. In this paper we present a short proof of the fact that any exact Lagrangian with vanishing Maslov class is homology equivalent to the base and that the induced map on fundamental groups is an isomorphism. When the fundamental group of the base is pro-finite this implies homotopy equivalence.

• 338.
Department of Mathematics, Bar-Ilan University, Ramat Gan, Israel.
Idempotent Geometry in Generic Algebras2018Inngår i: Advances in Applied Clifford Algebras, ISSN 0188-7009, E-ISSN 1661-4909, Vol. 28, nr 5, artikkel-id UNSP 84Artikkel i tidsskrift (Fagfellevurdert)

Using the syzygy method, established in our earlier paper (Krasnov and Tkachev, 2018), we characterize the combinatorial stratification of the variety of two-dimensional real generic algebras. We show that there exist exactly three different homotopic types of such algebras and relate this result to potential applications and known facts from qualitative theory of quadratic ODEs. The genericity condition is crucial. For example, the idempotent geometry in Clifford algebras or Jordan algebras of Clifford type is very different: such algebras always contain nontrivial submanifolds of idempotents.

• 339.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Legendrian Conormals of 2-Knots2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
• 340.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra och geometri.
Hurwitz 1, 2, 4, 8-sats2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
• 341.
Admissible transformations and the group classification of Schrödinger equations2017Doktoravhandling, med artikler (Annet vitenskapelig)

We study admissible transformations and solve group classification problems for various classes of linear and nonlinear Schrödinger equations with an arbitrary number n of space variables.

The aim of the thesis is twofold. The first is the construction of the new theory of uniform seminormalized classes of differential equations and its application to solving group classification problems for these classes. Point transformations connecting two equations (source and target) from the class under study may have special properties of semi-normalization. This makes the group classification of that class using the algebraic method more involved. To extend this method we introduce the new notion of uniformly semi-normalized classes. Various types of uniform semi-normalization are studied: with respect to the corresponding equivalence group, with respect to a proper subgroup of the equivalence group as well as the corresponding types of weak uniform semi-normalization. An important kind of uniform semi-normalization is given by classes of homogeneous linear differential equations, which we call uniform semi-normalization with respect to linear superposition of solutions.

The class of linear Schrödinger equations with complex potentials is of this type and its group classification can be effectively carried out within the framework of the uniform semi-normalization. Computing the equivalence groupoid and the equivalence group of this class, we show that it is uniformly seminormalized with respect to linear superposition of solutions. This allow us to apply the version of the algebraic method for uniformly semi-normalized classes and to reduce the group classification of this class to the classification of appropriate subalgebras of its equivalence algebra. To single out the classification cases, integers that are invariant under equivalence transformations are introduced. The complete group classification of linear Schrödinger equations is carried out for the cases n = 1 and n = 2.

The second aim is to study group classification problem for classes of generalized nonlinear Schrödinger equations which are not uniformly semi-normalized. We find their equivalence groupoids and their equivalence groups and then conclude whether these classes are normalized or not. The most appealing classes are the class of nonlinear Schrödinger equations with potentials and modular nonlinearities and the class of generalized Schrödinger equations with complex-valued and, in general, coefficients of Laplacian term. Both these classes are not normalized. The first is partitioned into an infinite number of disjoint normalized subclasses of three kinds: logarithmic nonlinearity, power nonlinearity and general modular nonlinearity. The properties of the Lie invariance algebras of equations from each subclass are studied for arbitrary space dimension n, and the complete group classification is carried out for each subclass in dimension (1+2). The second class is successively reduced into subclasses until we reach the subclass of (1+1)-dimensional linear Schrödinger equations with variable mass, which also turns out to be non-normalized. We prove that this class is mapped by a family of point transformations to the class of (1+1)-dimensional linear Schrödinger equations with unique constant mass.

• 342.
Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
Purity of Branch and Critical locus2013Inngår i: Journal of Algebra, ISSN 0021-8693, E-ISSN 1090-266X, Vol. 379, s. 156-178Artikkel i tidsskrift (Fagfellevurdert)

To a dominant morphism $X/S \to Y/S$ of N\oe therian integral $S$-schemes one has the inclusion $C_{X/Y}\subset B_{X/Y}$ of the critical locus in the branch locus of $X/Y$. Starting from the notion of locally complete intersection morphisms, we give conditions on the modules of relative differentials $\Omega_{X/Y}$, $\Omega_{X/S}$, and $\Omega_{Y/S}$ that imply bounds on the codimensions of $C_{X/Y}$ and $B_{X/Y}$. These bounds generalise to a wider class of morphisms the classical purity results for finite morphisms by Zariski-Nagata-Auslander, and Faltings and Grothendieck, and van der Waerden's purity for birational morphisms.

• 343.
University of Gävle, Department of Mathematics.
Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
Hilbert series of modules over Lie algebroidsArtikkel i tidsskrift (Fagfellevurdert)

We consider modules M over Lie algebroids g_A which are of  finite type over a local noetherian ring A.  Using ideals  J\subseteq A such that g_A . J \subseteq J  and the length  l_{g_A}(M/JM)< \infty we can define in a natural way the  Hilbert series of M with respect to the defining ideal J.  This  notion is in particular studied for modules over the Lie algebroid  of k-linear derivations g_A=T_A(I) that preserve an ideal  I\subseteq A, for example when A is the ring of convergent  power series.

• 344.
Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
Stockholms universitet.
Hilbert series of modules over Lie algebroids2015Inngår i: Journal of Algebra, ISSN 0021-8693, E-ISSN 1090-266X, Vol. 432, s. 129-184Artikkel i tidsskrift (Fagfellevurdert)

We consider modules M over Lie algebroids gA which are of finite type over a local noetherian ring A. Using ideals J ⊂ A such that gA ·J ⊂ J and the length ℓgA (M/JM) < ∞ we can define in a natural way the Hilbert series of M with respect to the defining ideal J. This notion is in particular studied for modules over the Lie algebroid of k-linear derivations gA = TA(I) that preserve an ideal I ⊂ A, for example when A = On, the ring of convergent power series. Hilbert series over Stanley-Reisner rings are also considered.

• 345.
Univ Stuttgart, Inst Algebra & Number Theory, D-70569 Stuttgart, Germany.
Auslander-Reiten theory of Frobenius-Lusztig kernels2013Inngår i: Bulletin of the London Mathematical Society, ISSN 0024-6093, E-ISSN 1469-2120, Vol. 45, nr 6, s. 1285-1300Artikkel i tidsskrift (Fagfellevurdert)

In this paper, we show that the tree class of a component of the stable Auslander–Reiten quiver of a Frobenius–Lusztig kernel is one of the three infinite Dynkin diagrams. For the special case of the small quantum group, we show that the periodic components are homogeneous tubes and that the non‐periodic components have shape ℤ[A] if the component contains a module for the infinite‐dimensional quantum group.

• 346.
Christian-Albrechts-Universität zu Kiel, Ludewig-Meyn-Str. 4, 24098 Kiel, Germany .
Auslander-Reiten theory of small half quantum groups2014Inngår i: Proceedings of the American Mathematical Society, ISSN 0002-9939, E-ISSN 1088-6826, Vol. 142, s. 1109-1119Artikkel i tidsskrift (Fagfellevurdert)

For the small half quantum groups u_\zeta(b) and u_\zeta(n) we show that the components of the stable Auslander-Reiten quiver containing gradable modules are of the form Z[A_\infty].

• 347.
Univ Kiel, D-24098 Kiel, Germany.
Biserial algebras via subalgebras and the path algebra of D42011Inngår i: Journal of Algebra, ISSN 0021-8693, E-ISSN 1090-266X, Vol. 331, nr 1, s. 58-67Artikkel i tidsskrift (Fagfellevurdert)

We give two new criteria for a basic algebra to be biserial. The first one states that an algebra is biserial iff all subalgebras of the form eAe where e is supported by at most 4 vertices are biserial. The second one gives some condition on modules that must not exist for a biserial algebra. These modules have properties similar to the module with dimension vector (1,1,1,1) for the path algebra of the quiver D4.

Both criteria generalize criteria for an algebra to be Nakayama. They rely on the description of a basic biserial algebra in terms of quiver and relations given by R. Vila-Freyer and W. Crawley-Boevey.

• 348. Külshammer, Julian
In the bocs seat: quasi-hereditary algebras and representation type2017Inngår i: Representation theory—current trends and perspectives / [ed] Henning Krause, Peter Littelmann, Gunter Malle, Karl-Hermann Neeb, Christoph Schweigert, European Mathematical Society Publishing House, 2017, s. 375-426Konferansepaper (Fagfellevurdert)

This paper surveys bocses, quasi-hereditary algebras and their relationship which was established in a recent result by Koenig, Ovsienko, and the author. Particular emphasis is placed on applications of this result to the representation type of the category filtered by standard modules for a quasi-hereditary algebra. In this direction, joint work with Thiel is presented showing that the subcategory of modules filtered by Weyl modules for tame Schur algebras is of finite representation type. The paper also includes a new proof for the classication of quasi-hereditary algebras with two simple modules, a result originally obtained by Membrillo–Hernández.

• 349.
Univ Stuttgart, Inst Algebra & Number Theory, Pfaffenwaldring 57, D-70569 Stuttgart, Germany.
Pro-species of algebras I: Basic properties2017Inngår i: Algebras and Representation Theory, ISSN 1386-923X, E-ISSN 1572-9079, Vol. 20, nr 5, s. 1215-1238Artikkel i tidsskrift (Fagfellevurdert)

In this paper, we generalise part of the theory of hereditary algebras to the context of pro-species of algebras. Here, a pro-species is a generalisation of Gabriel’s concept of species gluing algebras via projective bimodules along a quiver to obtain a new algebra. This provides a categorical perspective on a recent paper by Geiß et al. (2016). In particular, we construct a corresponding preprojective algebra, and establish a theory of a separated pro-species yielding a stable equivalence between certain functorially finite subcategories.

• 350.
Christian-Albrechts-Universität zu Kiel, Ludewig-Meyn-Str. 4, 24098 Kiel, Germany.
Representation type of Frobenius-Lusztig kernels2013Inngår i: Quarterly Journal of Mathematics, ISSN 0033-5606, E-ISSN 1464-3847, Vol. 64, nr 2, s. 471-488Artikkel i tidsskrift (Fagfellevurdert)

In this article, we show that almost all blocks of all Frobenius–Lusztig kernels are of wild representation type extending results of Feldvoss and Witherspoon, who proved this result for the principal block of the zeroth Frobenius–Lusztig kernel. Furthermore, we verify the conjecture that there are infinitely many Auslander–Reiten components for a finite-dimensional algebra of infinite representation type for selfinjective algebras whose cohomology satisfies certain finiteness conditions.

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