English

On two problems in Ramsey-Tur\'an theory

Combinatorics 2017-04-25 v2

Abstract

Alon, Balogh, Keevash and Sudakov proved that the (k1)(k-1)-partite Tur\'an graph maximizes the number of distinct rr-edge-colorings with no monochromatic KkK_k for all fixed kk and r=2,3r=2,3, among all nn-vertex graphs. In this paper, we determine this function asymptotically for r=2r=2 among nn-vertex graphs with sub-linear independence number. Somewhat surprisingly, unlike Alon-Balogh-Keevash-Sudakov's result, the extremal construction from Ramsey-Tur\'an theory, as a natural candidate, does not maximize the number of distinct edge-colorings with no monochromatic cliques among all graphs with sub-linear independence number, even in the 2-colored case. In the second problem, we determine the maximum number of triangles asymptotically in an nn-vertex KkK_k-free graph GG with α(G)=o(n)\alpha(G)=o(n). The extremal graphs have similar structure to the extremal graphs for the classical Ramsey-Tur\'an problem, i.e.~when the number of edges is maximized.

Keywords

Cite

@article{arxiv.1607.06393,
  title  = {On two problems in Ramsey-Tur\'an theory},
  author = {József Balogh and Hong Liu and Maryam Sharifzadeh},
  journal= {arXiv preprint arXiv:1607.06393},
  year   = {2017}
}

Comments

22 pages

R2 v1 2026-06-22T15:00:47.406Z