## Topology & Geometric Group Theory Seminar

## Fall 2010

### 1:30 – 2:30, Malott 253

Tuesday, November 30

**Patricia Hersh**,
North Carolina State University and Cornell University

*Shelling Coxeter-like complexes and sorting on trees*

Given any finite Coxeter group and any minimal set S of generators,
Eric Babson and Vic Reiner introduced an associated ``Coxeter-like
complex'' whose cells are cosets of ``parabolic subgroups'',
i.e. subgroups generated by a subset of S. They conjectured a lower
bound on the connectivity in the case where W is the symmetric group
and S is a set of transpositions. I will discuss the proof of this
conjecture and how this relates to the question of which trees admit
pleasant notions of inversions and weak order on the set of labelings
of the tree.

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