Now showing items 1-20 of 36

• #### Calculating conjugacy classes in Sylow p-subgroups of finite Chevalley groups of rank six and seven ﻿

[OWP-2013-10] (Mathematisches Forschungsinstitut Oberwolfach, 2013-04-10)
Let $G(q)$ be a finite Chevalley group, where $q$ is a power of a good prime $p$, and let $U(q)$ be a Sylow $p$-subgroup of $G(q)$. Then a generalized version of a conjecture of Higman asserts that the number $k(U(q))$ of ...
• #### Cataland: Why the Fuß? ﻿

[OWP-2019-01] (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. ...
• #### Categoric Aspects of Authentication ﻿

[OWP-2012-05] (Mathematisches Forschungsinstitut Oberwolfach, 2012-04-24)
• #### Cocharacter-closure and spherical buildings ﻿

[OWP-2015-12] (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
Let $k$ be a field, let $G$ be a reductive $k$-group and $V$ an affine $k$-variety on which $G$ acts. In this note we continue our study of the notion of cocharacter-closed $G(k)$-orbits in $V$. In earlier work we used a ...
• #### Cocharacter-Closure and the Rational Hilbert-Mumford Theorem ﻿

[OWP-2014-16] (Mathematisches Forschungsinstitut Oberwolfach, 2014-12-20)
For a field $k$, let $G$ be a reductive $k$-group and $V$ an affine $k$-variety on which $G$ acts. Using the notion of cocharacter-closed $G(k)$-orbits in $V$ , we prove a rational version of the celebrated Hilbert-Mumford ...
• #### Computing Congruence Quotients of Zariski Dense Subgroups ﻿

[OWP-2018-22] (Mathematisches Forschungsinstitut Oberwolfach, 2018-10-26)
• #### Linear Syzygies, Hyperbolic Coxeter Groups and Regularity ﻿

[OWP-2017-15] (Mathematisches Forschungsinstitut Oberwolfach, 2017-05-24)
We build a new bridge between geometric group theory and commutative algebra by showing that the virtual cohomological dimension of a Coxeter group is essentially the regularity of the Stanley–Reisner ring of its nerve. ...
• #### The Magic Square of Reflections and Rotations ﻿

[OWP-2018-13] (Mathematisches Forschungsinstitut Oberwolfach, 2018-07-01)
We show how Coxeter’s work implies a bijection between complex reflection groups of rank two and real reflection groups in 0(3). We also consider this magic square of reflections and rotations in the framework of Clifford ...
• #### New representations of matroids and generalizations ﻿

[OWP-2011-18] (Mathematisches Forschungsinstitut Oberwolfach, 2011)
We extend the notion of matroid representations by matrices over fields by considering new representations of matroids by matrices over finite semirings, more precisely over the boolean and the superboolean semirings. This ...