“An EL-shelling of the
subgroup lattice”

Russ Woodroofe

(University of
Washington)

ABSTRACT:
In a 2001 paper, Shareshian proved that the subgroup
lattice of a finite group G is shellable if and only if G is solvable. The
``if'' direction of his proof relied on a coatom ordering, and he conjectured
the existence of an EL-labeling, which would link shellability with earlier
topological results of Thevenaz. After describing the background and history of
the problem, I will show how to extend results from supersolvable
(left-modular) lattices to construct the conjectured EL-labeling.

Date : April 8, 2008 (Tuesday)

Time : 15:40 – 17:00

Place: Mathematics Seminar Room SA141