The University of Michigan Combinatorics Seminar
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Abstract |
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The symmetric group Sn acts on the lattice
Pin of partitions of [n]
into subsets in the obvious
way, and this action determines a representation of Sn
on the unique nontrivial homology group of the order
complex of Pin. Results of Hanlon and Stanley show
that this representation is obtained by tensoring with
the alternating representation the representation of Sn
on the subspace of the Free Lie algebra on n variables
generated by Lie words in which each varibale appears
exactly once (thus the name Lie representation). In
addition, the Lie represenation is induced from a faithful
representation of the subgroup generated by any n-cycle
in Sn. I will discuss my efforts to find analogous
represenations for GLn(q) and other classical finite
groups.
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