English

Monochromatic triangle-tilings in dense graphs without large independent sets

Combinatorics 2026-01-27 v1

Abstract

Given two graphs HH and GG, an HH-tiling is a family of vertex-disjoint copies of HH in GG. A perfect HH-tiling covers all vertices of GG. The Corradi-Hajnal theorem (1963) states that an nn-vertex graph GG with minimum degree δ(G)2n/3\delta(G)\ge 2n/3 contains a perfect triangle-tiling. For an nn-vertex graph GG with independence number α(G)=o(n)\alpha(G)=o(n), Balogh, Molla and Sharifzadeh (Random Structures & Algorithms, 2016) showed that a minimum degree of (12+o(1))n(\frac12+o(1))n forces a perfect triangle-tiling. In a 2-edge-colored graph, Balogh, Freschi, Treglown (European J. Combin. 2026) determined the (asymptotic) minimum degree threshold for forcing a strong or weak monochromatic triangle-tiling covering a prescribed proportion of the vertices: a strong tiling requires all triangles to be in the same color class, while a weak tiling only requires each triangle to be monochromatic. In this paper, we combine the conditions from these two lines of work and prove that every 22-edge-colored nn-vertex graph GG with α(G)=o(n)\alpha(G)=o(n) contains a weak monochromatic triangle-tiling Γ\Gamma of size Γ{2δ(G)no(n),if 12nδ(G)35n,δ(G)/3o(n),if δ(G)>35n. |\Gamma|\ge \begin{cases} 2\delta(G)-n-o(n), & \text{if }\frac12 n\le \delta(G)\le \frac35 n,\\[2mm] \delta(G)/3-o(n), & \text{if }\delta(G)>\frac35 n. \end{cases} Both bounds are asymptotically optimal. We use the degree form regularity lemma in our proof.

Keywords

Cite

@article{arxiv.2601.18565,
  title  = {Monochromatic triangle-tilings in dense graphs without large independent sets},
  author = {Xinmin Hou and Xiangyang Wang and Zhi Yin},
  journal= {arXiv preprint arXiv:2601.18565},
  year   = {2026}
}

Comments

21 pages, 1 figure

R2 v1 2026-07-01T09:20:33.380Z