Colloquium April 17
Date: Friday, April 17
Time: 16:00 to 17:00
Place: 455 McBryde (Commons Room)
Speaker: Patricia Hersh of NC State Univ
Title: Combinatorics and topology of regular CW complexes
Abstract: Anders Bjorner characterized which finite, graded partially ordered sets are closure posets of regular CW complexes, and he also observed that a regular CW complex is homeomorphic to the order complex of its closure poset. This suggests that one might use combinatorics to determine topological structure; however, it is possible for two different CW complexes with very different topological structure to have the same closure poset if one of them is not regular. I will talk about a new criterion for determining whether a finite CW complex is regular; this will involve a mixture of combinatorics and topology. Along the way, I will review the notions from topology and combinatorics we will need. Finally, I will discuss an application to totally positive spaces having intervals in Bruhat order as their closure posets.
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