Richardson varieties (the intersections of Schubert with opposite
Schubert varieties) have interesting singularities. I'll give two
"anticanonical simple normal crossings divisor (sncd)" resolutions of
their singularities: Brion's using Escobar's "brick manifolds", and a
new (choiceless!) one using a space of equivariant stable maps.
Folk-conjecturally, the simplicial-complex dual (which I'll recall) of
an anticanonical sncd is homotopic to a sphere modulo a finite group.
I'll show that both sncds have duals that are actually homeomorphic to
spheres, one a subword complex and the other (essentially) the
Bj\"orner-Wachs order complex of an open Bruhat interval.
Room: BA 1200