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An entropy proof of the commonality of apices of trees
Abstract
A graph H is called common if the number of monochromatic copies of H in a $2$-edge-colouring of a large complete graph is asymptotically minimized by the random colouring with an equal proportion of each colour. Grzesik, Lee, Lidický and Volec conjectured that every k-apex of any connected Sidorenko graph is common. Recently, Kr{á}l', Krnc and Lamaison proved that the k-apex of any tree is common for k≤ 5. In this paper, we extend their result by showing that for every positive integer k, the k-apex of any tree or any forest with average degree at least one is common. Our proof involves an application of the entropy method.
Related
BibTeX
@misc{chen2026entropy,
title = {{An entropy proof of the commonality of apices of trees}},
author = {Hao Chen},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29469},
eprint = {2610.29469},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29469},
}
RIS
TY - UNPB
TI - An entropy proof of the commonality of apices of trees
AU - Hao Chen
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29469
UR - https://arxiv.org/abs/2610.29469
AB - A graph H is called common if the number of monochromatic copies of H in a $2$-edge-colouring of a large complete graph is asymptotically minimized by the random colouring with an equal proportion of each colour. Grzesik, Lee, Lidický and Volec conjectured that every k-apex of any connected Sidorenko graph is common. Recently, Kr{á}l', Krnc and Lamaison proved that the k-apex of any tree is common for k≤ 5. In this paper, we extend their result by showing that for every positive integer k, the k-apex of any tree or any forest with average degree at least one is common. Our proof involves an application of the entropy method.
ER -