“An EL-shelling of the subgroup lattice”
(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