Browsing 2019 by MSC "16"

Now showing items 1-5 of 5

    • 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. ...

    • 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, ...

    • 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 ...

    • On the Lie Algebra Structure of $HH^1(A)$ of a Finite-Dimensional Algebra A 

      [OWP-2019-10] Linckelmann, Markus; Rubio y Degrassi, Lleonard (Mathematisches Forschungsinstitut Oberwolfach, 2019-04-17)
      Let $A$ be a split finite-dimensional associative unital algebra over a field. The first main result of this note shows that if the Ext-quiver of $A$ is a simple directed graph, then $HH^1(A)$ is a solvable Lie algebra. ...

    • Weighted Surface Algebras: General Version 

      [OWP-2019-07] Erdmann, Karin; Skowroński, Andrzej (Mathematisches Forschungsinstitut Oberwolfach, 2019-02-28)
      We introduce general weighted surface algebras of triangulated surfaces with arbitrarily oriented triangles and describe their basic properties. In particular, we prove that all these algebras, except the singular disc, ...