4 papers
The Poincaré Series of Coxeter Folding Subgroups
Camilo Augusto Villamil Chalarca, Edward Richmond
Folding subgroups give a way to realize non-simply-laced Coxeter groups as subgroups of simply-laced Coxeter groups. In this paper, we study how folding subgroups of finite and aff…
Coxeter groups and Billey-Postnikov decompositions
Suho Oh, Edward Richmond
In this chapter, we give an overview of Billey-Postnikov (BP) decompositions which have become an important tool for understanding the geometry and combinatorics of Schubert variet…
Enumerating Permutations Avoiding Split Patterns 3|12 and 23|1
Travis Grigsby, Edward Richmond
In this paper, we give a formula for the number of permutations that avoid the split patterns and with respect to a position . Such permutations count the number o…
Nil-Hecke rings and the Schubert calculus
Edward Richmond, Kirill Zainoulline
The purpose of the present notes is to give a self-contained exposition on the use of the techniques of Nil-Hecke algebras in the localization approach to the equivariant Schubert…