Whitney Homology of Semipure Shellable Posets

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

We generalize results of Calderbank, Hanlon and Robinson on the representation of the symmetric group on the homology of posets of partitions with restricted block size. Calderbank, Hanlon and Robinson consider the cases of block sizes that are congruent to 0 mod d and 1 mod d for fixed d. We derive a general formula for the representation of the symmetric group on the homology of posets of partitions whose block sizes are congruent to k mod d for any k and d. This formula reduces to the Calderbank-Hanlon-Robinson formulas when k = 0, 1 and to formulas of Sundaram for the virtual representation on the alternating sum of homology. Our results apply to restricted block size partition posets even more general than the k mod d partition posets. These posets include the lattice of partitions whose block sizes are bounded from below by some fixed k. Our main tools involve the new theory of nonpure shellability developed by Björner and Wachs and a generalization of a technique of Sundaram which uses Whitney homology to compute homology representations of Cohen-Macaulay posets. An application to subspace arrangements is also discussed.

Original languageEnglish (US)
Pages (from-to)173-207
Number of pages35
JournalJournal of Algebraic Combinatorics
Volume9
Issue number2
DOIs
StatePublished - Jan 1 1999

Keywords

  • Plethysm
  • Poset homology
  • Shellable

ASJC Scopus subject areas

  • Algebra and Number Theory
  • Discrete Mathematics and Combinatorics

Fingerprint Dive into the research topics of 'Whitney Homology of Semipure Shellable Posets'. Together they form a unique fingerprint.

  • Cite this