RELATIVE LERAY NUMBERS VIA SPECTRAL SEQUENCES

Gil Kalai, Roy Meshulam*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Let (Formula presented.) be a fixed field and let X be a simplicial complex on the vertex set V. The Leray number (Formula presented.) is the minimal d such that for all (Formula presented.) and (Formula presented.), the induced complex (Formula presented.) satisfies (Formula presented.). Leray numbers play a role in formulating and proving topological Helly-type theorems. For two complexes (Formula presented.) on the same vertex set V, define the relative Leray number (Formula presented.) as the minimal d such that (Formula presented.) for all (Formula presented.) and (Formula presented.). In this paper we extend the topological colorful Helly theorem to the relative setting. Our main tool is a spectral sequence for the intersection of complexes indexed by a geometric lattice.

Original languageEnglish
Pages (from-to)730-737
Number of pages8
JournalMathematika
Volume67
Issue number3
DOIs
StatePublished - Jul 2021

Bibliographical note

Publisher Copyright:
© 2021 The Authors. The publishing rights for this article are licensed to University College London under an exclusive licence.

Keywords

  • 52A35
  • 55U10

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