Tur\'an, involution and shifting
Combinatorics
2018-02-13 v1
Abstract
We propose a strengthening of the conclusion in Tur\'an's (3,4)-conjecture in terms of algebraic shifting, and show that its analogue for graphs does hold. In another direction, we generalize the Mantel-Tur\'an theorem by weakening its assumption: for any graph G on n vertices and any involution on its vertex set, if for any 3-set S of the vertices, the number of edges in G spanned by S, plus the number of edges in G spanned by the image of S under the involution, is at least 2, then the number of edges in G is at least the Mantel-Tur\'an bound, namely the number achieved by two disjoint cliques of sizes n/2 rounded up and down.
Keywords
Cite
@article{arxiv.1802.03648,
title = {Tur\'an, involution and shifting},
author = {Gil Kalai and Eran Nevo},
journal= {arXiv preprint arXiv:1802.03648},
year = {2018}
}