• Abstract Bivariant Cuntz Semigroups 

      [OWP-2017-04] Antoine, Ramon; Perera, Francesc; Thiel, Hannes (Mathematisches Forschungsinstitut Oberwolfach, 2017-02-13)
      We show that abstract Cuntz semigroups form a closed symmetric monoidal category. Thus, given Cuntz semigroups $S$ and $T$, there is another Cuntz semigroup $((S,T))$ playing the role of morphisms from $S$ to $T$. Applied ...
    • The algebra of differential operators for a Gegenbauer weight matrix 

      [OWP-2015-07] Ignacio Nahuel Zurrián (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
      In this work we study in detail the algebra of differential operators $\mathcal{D}(W)$ associated with a Gegenbauer matrix weight. We prove that two second order operators generate the algebra, indeed $\mathcal{D}(W)$ is ...
    • Cataland: Why the Fuß? 

      [OWP-2019-01] Stump, Christian; Thomas, Hugh; Williams, Nathan (Mathematisches Forschungsinstitut Oberwolfach, 2019-01-21)
      The three main objects in noncrossing Catalan combinatorics associated to a finite Coxeter system are noncrossing partitions, clusters, and sortable elements. The first two of these have known Fuß-Catalan generalizations. ...
    • 1012 - Combinatorial Representation Theory 

      [OWR-2010-15] (2010) - (21 Mar - 27 Mar 2010)
      The workshop brought together researchers from different fields in representation theory and algebraic combinatorics for a fruitful interaction. New results, methods and developments ranging from classical and modular ...
    • Composition of Irreducible Morphisms in Coils 

      [OWP-2017-32] Chaio, Claudia; Malicki, Piotr (Mathematisches Forschungsinstitut Oberwolfach, 2017-10-30)
      We study the non-zero composition of n irreducible morphisms between modules lying in coils in relation with the powers of the radical of their module category.
    • Composition of Irreducible Morphisms in Quasi-Tubes 

      [OWP-2015-03] Chaio, Claudia; Malicki, Piotr (Mathematisches Forschungsinstitut Oberwolfach, 2015-04-09)
      We study the composition of irreducible morphisms between indecomposable modules lying in quasi-tubes of the Auslander-Reiten quivers of artin algebras $A$ in relation with the powers of the radical of their module category ...
    • 1131 - Computational Group Theory 

      [OWR-2011-37] (2011) - (31 Jul - 06 Aug 2011)
      This sixth workshop on Computational Group Theory proved that its main themes “finitely presented groups”, “$p$-groups”, “matrix groups” and “representations of groups” are lively and active fields of research. The talks ...
    • 1631 - Computational Group Theory 

      [OWR-2016-37] (2016) - (31 Jul - 06 Aug 2016)
      This was the seventh workshop on Computational Group Theory. It showed that Computational Group Theory has significantly expanded its range of activities. For example, symbolic computations with groups and their representations ...
    • 0605 - Convex and Algebraic Geometry 

      [OWR-2006-5] (2006) - (29 Jan - 04 Feb 2006)
      The subjects of convex and algebraic geometry meet primarily in the theory of toric varieties. Toric geometry is the part of algebraic geometry where all maps are given by monomials in suitable coordinates, and all equations ...
    • 1039 - Deformation Methods in Mathematics and Physics 

      [OWR-2010-43] (2010) - (26 Sep - 01 Oct 2010)
      Deformations of mathematical structures play an important role in most parts of mathematics but also in theoretical physics. In this interdisciplinary workshop, different aspects of deformations and their applications were ...
    • 0603 - Deformations and Contractions in Mathematics and Physics 

      [OWR-2006-3] (2006) - (15 Jan - 21 Jan 2006)
      Deformations of mathematical structures are not only important in most parts of mathematics but also to a large extend in physics. Contractions are in some respect dual to deformations. The workshop brought together world ...
    • Dominance and Transmissions in Supertropical Valuation Theory 

      [OWP-2011-07] Izhakian, Zur; Knebusch, Manfred; Rowen, Louis (Mathematisches Forschungsinstitut Oberwolfach, 2011)
      This paper is a sequel of [IKR1], where we defined supervaluations on a commutative ring $R$ and studied a dominance relation $\Phi >= v$ between supervaluations $\varphi$ and $\upsilon$ on $R$, aiming at an enrichment of ...
    • The First Hochschild Cohomology as a Lie Algebra 

      [OWP-2019-09] Rubio y Degrassi, Lleonard; Schroll, Sibylle; Solotar, Andrea (Mathematisches Forschungsinstitut Oberwolfach, 2019-04-16)
      In this paper we study sufficient conditions for the solvability of the first Hochschild cohomology of a finite dimensional algebra as a Lie algebra in terms of its Ext-quiver in arbitrary characteristic. In particular, ...
    • Fundamental Theorem of Projective Geometry over Semirings 

      [OWP-2021-09] Tewari, Ayush Kumar (Mathematisches Forschungsinstitut Oberwolfach, 2021-10-11)
      We state the fundamental theorem of projective geometry for semimodules over semirings, which is facilitated by recent work in the study of bases in semimodules defined over semirings. In the process we explore in detail ...
    • Geometry of Free Loci and Factorization of Noncommutative Polynomials 

      [OWP-2017-23] Helton, J. William; Klep, Igor; Volčič, Jurij; Helton, J. William (Mathematisches Forschungsinstitut Oberwolfach, 2017-10-02)
      The free singularity locus of a noncommutative polynomial f is defined to be the sequence $Z_n(f)=\{X\in M_n^g : \det f(X)=0\}$ of hypersurfaces. The main theorem of this article shows that f is irreducible if and only if ...
    • Group-Graded Rings Satisfying the Strong Rank Condition 

      [OWP-2019-22] Kropholler, Peter H.; Lorensen, Karl (Mathematisches Forschungsinstitut Oberwolfach, 2019-08-16)
      A ring $R$ satisfies the $\textit{strong rank condition}$ (SRC) if, for every natural number $n$, the free $R$-submodules of $R^n$ all have rank $\leq n$. Let $G$ be a group and $R$ a ring strongly graded by $G$ such that ...
    • 1607b - Hochschild Cohomology in Algebra, Geometry, and Topology 

      [OWR-2016-10] (2016) - (14 Feb - 20 Feb 2016)
      In 1945 Gerhard Hochschild published "On the cohomology groups of an associative algebra" in the Annals of Mathematics and thereby created what is now called Hochschild theory. In 1963, Murray Gerstenhaber proved that the ...
    • Homological properties of piecewise hereditary algebras 

      [OWP-2009-11] Happel, Dieter; Zacharia, Dan (Mathematisches Forschungsinstitut Oberwolfach, 2009-03-05)
      Let $\Lambda$ be a finite dimensional algebra over an algebraically closed field $k$. We will investigate homological properties of piecewise hereditary algebras $\Lambda$. In particular we give lower and upper bounds of ...
    • 0619 - Interactions between Algebraic Geometry and Noncommutative Algebra 

      [OWR-2006-23] (2006) - (07 May - 13 May 2006)
      The workshop discussed the interactions between algebraic geometry and various areas of noncommutative algbebra including finite dimensional algebras, representation theory of algebras and noncommutative algebraic geometry. ...
    • 1019 - Interactions between Algebraic Geometry and Noncommutative Algebra 

      [OWR-2010-22] (2010) - (09 May - 15 May 2010)
      The aim of this workshop was to communicate the most current developments in the field of noncommutative algebra and its interactions with algebraic geometry and representation theory.