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Let $\mathscr{G}$ be the class of plane graphs without triangles normally adjacent to $8^{-}$-cycles, without $4$-cycles normally adjacent to $6^{-}$-cycles, and without normally adjacent $5$-cycles. In this paper, it is shown that every…

Combinatorics · Mathematics 2022-06-13 Fangyao Lu , Mengjiao Rao , Qianqian Wang , Tao Wang

We construct $n$-vertex graphs $G$ where $\epsilon n^2$ edges must be deleted to become triangle-free, which contain less than $\epsilon^{(C_{\text{new}}-o(1))\log_2 1/\epsilon}n^3$ triangles for $C_{\text{new}}= \frac{1}{4\log_2(4/3)}…

Combinatorics · Mathematics 2025-07-08 Zach Hunter

We show that, for every $k \ge 2$, every $k$-uniform hypergaph of degree $\Delta$ and girth at least $5$ is efficiently $(1+o(1) )(k-1) (\Delta / \ln \Delta )^{ 1/(k-1) } $-list colorable. As an application (and to the best of our…

Discrete Mathematics · Computer Science 2026-02-10 Fotis Iliopoulos

We prove an asymptotically tight lower bound on the average size of independent sets in a triangle-free graph on $n$ vertices with maximum degree $d$, showing that an independent set drawn uniformly at random from such a graph has expected…

Combinatorics · Mathematics 2018-01-25 Ewan Davies , Matthew Jenssen , Will Perkins , Barnaby Roberts

Recently, settling a question of Erd\H{o}s, Balogh and Pet\v{r}\'{i}\v{c}kov\'{a} showed that there are at most $2^{n^2/8+o(n^2)}$ $n$-vertex maximal triangle-free graphs, matching the previously known lower bound. Here we characterize the…

Combinatorics · Mathematics 2016-08-07 József Balogh , Hong Liu , Šárka Petříčková , Maryam Sharifzadeh

Analogues of Ramsey's Theorem for infinite structures such as the rationals or the Rado graph have been known for some time. In this context, one looks for optimal bounds, called degrees, for the number of colors in an isomorphic…

Combinatorics · Mathematics 2022-06-03 Natasha Dobrinen

We study quantitative relationships between the triangle removal lemma and several of its variants. One such variant, which we call the triangle-free lemma, states that for each $\epsilon>0$ there exists $M$ such that every triangle-free…

Combinatorics · Mathematics 2022-01-17 Jacob Fox , Yufei Zhao

The adaptable choosability of a multigraph $G$, denoted $\mathrm{ch}_a(G)$, is the smallest integer $k$ such that any edge labelling, $\tau$, of $G$ and any assignment of lists of size $k$ to the vertices of $G$ permits a list colouring,…

Combinatorics · Mathematics 2021-07-12 Jurgen Aliaj , Michael Molloy

We show that there is a constant $k$ such that when $r \geq 2$ and $m \geq r^k$, the complete $r$-partite graph $K_{m*r}$ has a non-colorable list assignment $L$ such that $|L(v)| \geq \frac{7}{750}r\ln m$ for all $v$ and such that $|L(u)…

Combinatorics · Mathematics 2014-03-24 Gregory J. Puleo

The widely studied edge modification problems ask how to minimally alter a graph to satisfy certain structural properties. In this paper, we introduce and study a new edge modification problem centered around transforming a given graph into…

Data Structures and Algorithms · Computer Science 2025-09-16 Amirali Madani , Anil Maheshwari , Babak Miraftab , Paweł Żyliński

We prove Tur\'an-type theorems for two related Ramsey problems raised by Bollob\'as and by Fox and Sudakov. First, for $t \ge 3$, we show that any two-colouring of the complete graph on $n$ vertices that is $\delta$-far from being…

Combinatorics · Mathematics 2019-07-02 António Girão , Bhargav Narayanan

It is shown that any graph with maximum degree $\Delta$ in which the average degree of the induced subgraph on the set of all neighbors of any vertex exceeds $\frac{6k^2}{6k^2 + 1}\Delta + k + 6$ is either $(\Delta - k)$-colorable or…

Combinatorics · Mathematics 2012-10-02 Landon Rabern

We consider extensions of Brooks' classic theorem on vertex coloring where some colors cannot be used on certain vertices. In particular we prove that if $G$ is a connected graph with maximum degree $\Delta(G) \geq 4$ that is not a complete…

Combinatorics · Mathematics 2023-03-14 Carl Johan Casselgren

it is shown that each triangle-free 1-planar graph with maximum degree $\Delta\geq7$ can be $\Delta$-colorable by Discharging Method.

Combinatorics · Mathematics 2010-12-30 Xin Zhang , Guizhen Liu , Jian-Liang Wu

Recently, Milani\v{c} and Trotignon introduced the class of equistarable graphs as graphs without isolated vertices admitting positive weights on the edges such that a subset of edges is of total weight $1$ if and only if it forms a maximal…

Combinatorics · Mathematics 2015-02-24 Endre Boros , Nina Chiarelli , Martin Milanič

An identifying code of a closed-twin-free graph $G$ is a dominating set $S$ of vertices of $G$ such that any two vertices in $G$ have a distinct intersection between their closed neighborhoods and $S$. It was conjectured that there exists…

Combinatorics · Mathematics 2025-10-13 Dipayan Chakraborty , Florent Foucaud , Michael A. Henning , Tuomo Lehtilä

We present a randomized algorithm that, given a constant $\epsilon > 0$, outputs a proper $(1+\epsilon)\Delta$-edge-coloring of an $m$-edge simple graph $G$ of maximum degree $\Delta \geq 1/\epsilon$ in $O(m)$ time with high probability.…

Data Structures and Algorithms · Computer Science 2025-02-10 Anton Bernshteyn , Abhishek Dhawan

A simplicial complex of dimension $d-1$ is said to be balanced if its graph is $d$-colorable. Juhnke-Kubitzke and Murai proved an analogue of the generalized lower bound theorem for balanced simplicial polytopes. We establish a…

Combinatorics · Mathematics 2016-08-30 Martina Juhnke-Kubitzke , Satoshi Murai , Isabella Novik , Connor Sawaske

We make progress on a number of open problems concerning the area requirement for drawing trees on a grid. We prove that 1. every tree of size $n$ (with arbitrarily large degree) has a straight-line drawing with area $n2^{O(\sqrt{\log\log…

Computational Geometry · Computer Science 2018-03-21 Timothy M. Chan

In 1991 Gy\H ori, Pach, and Simonovits proved that for any bipartite graph $H$ containing a matching avoiding at most 1 vertex, the maximum number of copies of $H$ in any large enough triangle-free graph is achieved in a balanced complete…

Combinatorics · Mathematics 2023-09-25 Dmitriy Gorovoy , Andrzej Grzesik , Justyna Jaworska