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We strengthen a result of Dross, Montassier and Pinlou (2017) that the vertex set of every triangle-free planar graph can be decomposed into a set that induces a forest and a set that induces a forest with maximum degree at most $5$,…

Combinatorics · Mathematics 2023-02-07 Carl Feghali , Robert Šámal

A linear forest is an acyclic graph whose each connected component is a path; or in other words, it is an acyclic graph whose maximum degree is at most 2. A linear coloring of a graph $G$ is an edge coloring of $G$ such that the edges in…

Combinatorics · Mathematics 2023-08-16 Manu Basavaraju , Arijit Bishnu , Mathew Francis , Drimit Pattanayak

An equitable $(t,k,d)$-tree-coloring of a graph $G$ is a coloring to vertices of $G$ such that the sizes of any two color classes differ by at most one and the subgraph induced by each color class is a forest of maximum degree at most $k$…

Combinatorics · Mathematics 2012-11-20 Jian-Liang Wu , Xin Zhang , Hailun Li

The following measure of sparsity of multigraphs refining the maximum average degree: For $a>0$ and an arbitrary real $b$, a multigraph $H$ is \emph{$(a,b)$-sparse} if it is loopless and for every $A\subseteq V(H)$ with $|A|\geq 2$, the…

Combinatorics · Mathematics 2025-05-26 Ilkyoo Choi , Alexandr V. Kostochka , Matthew Yancey

It is well-known that there exists a triangle-free planar graph of $n$ verticess such that the largest induced forest has size at most $\frac{5n}{8}$. Salavatipour proved that there is a forest of size at least $\frac{5n}{9.41}$ in any…

Combinatorics · Mathematics 2017-01-27 Hung Le

For \math{p\ge 1}, we prove that every forest with \math{p} trees whose sizes are $a_1,..., a_p$ can be embedded in any graph containing at least $\sum_{i=1}^p (a_i + 1)$ vertices and having a minimum degree at least $\sum_{i=1}^p a_i$.

Combinatorics · Mathematics 2010-11-18 Mark Goldberg , Malik Magdon-Ismail

A common problem in graph colouring seeks to decompose the edge set of a given graph into few similar and simple subgraphs, under certain divisibility conditions. In 1987 Wormald conjectured that the edges of every cubic graph on $4n$…

Combinatorics · Mathematics 2025-07-09 Gal Kronenberg , Shoham Letzter , Alexey Pokrovskiy , Liana Yepremyan

Chernyshev, Rauch, and Rautenbach proved that every connected graph on $n$ vertices with less than $\frac{11}{5}n-\frac{18}{5}$ edges has a vertex cut that induces a forest, and conjectured that the same remains true if the graph has less…

Combinatorics · Mathematics 2025-05-27 F. Botler , Y. S. Couto , C. G. Fernandes , E. F. de Figueiredo , R. Gómez , V. F. dos Santos , C. M. Sato

A linear forest is a collection of vertex-disjoint paths. The Linear Arboricity Conjecture states that every graph of maximum degree $\Delta$ can be decomposed into at most $\lceil(\Delta+1)/2\rceil$ linear forests. We prove that $\Delta/2…

Combinatorics · Mathematics 2025-07-29 Micha Christoph , Nemanja Draganić , António Girão , Eoin Hurley , Lukas Michel , Alp Müyesser

It is well-known that every planar or projective planar graph can be 3-colored so that each color class induces a forest. This bound is sharp. In this paper, we show that there are in fact exponentially many 3-colorings of this kind for any…

Combinatorics · Mathematics 2011-10-25 Ararat Harutyunyan , Bojan Mohar

A proper vertex coloring of a simple graph is $k$-forested if the graph induced by the vertices of any two color classes is a forest with maximum degree less than $k$. A graph is $k$-forested $q$-choosable if for a given list of $q$ colors…

Combinatorics · Mathematics 2011-02-22 Xin Zhang , Guizhen Liu , Jian-Liang Wu

For a graph $G$, let $a(G)$ denote the maximum size of a subset of vertices that induces a forest. We prove the following. 1. Let $G$ be a graph of order $n$, maximum degree $\Delta>0$ and maximum clique size $\omega$. Then \[ a(G) \geq…

Combinatorics · Mathematics 2019-10-04 Shimon Kogan

The equitable coloring problem, introduced by Meyer in 1973, has received considerable attention and research. Recently, Wu, Zhang and Li introduced the concept of equitable $(t,k)$-tree-coloring, which can be regarded as a generalization…

Combinatorics · Mathematics 2016-02-16 Yaping Mao , Zhiwei Guo , Hongjian Lai , Haixing Zhao

A signed tree-coloring of a signed graph $(G,\sigma)$ is a vertex coloring $c$ so that $G^{c}(i,\pm)$ is a forest for every $i\in c(u)$ and $u\in V(G)$, where $G^{c}(i,\pm)$ is the subgraph of $(G,\sigma)$ whose vertex set is the set of…

Combinatorics · Mathematics 2017-08-11 Weichan Liu , Chen Gong , Lifang Wu , Xin Zhang

A \emph{tree-partition} of a graph $G$ is a proper partition of its vertex set into `bags', such that identifying the vertices in each bag produces a forest. The \emph{tree-partition-width} of $G$ is the minimum number of vertices in a bag…

Combinatorics · Mathematics 2009-04-02 David R. Wood

In this article, we study the order and structure of the largest induced forests in some families of graphs. First we prove a variation of the ratio bound that gives an upper bound on the order of the largest induced forest in a graph. Next…

Combinatorics · Mathematics 2024-04-17 Karen Gunderson , Karen Meagher , Joy Morris , Venkata Raghu Tej Pantangi

An \emph{equitable $(q, r)$-tree-coloring} of a graph $G$ is a $q$-coloring of $G$ such that the subgraph induced by each color class is a forest of maximum degree at most $r$ and the sizes of any two color classes differ by at most $1.$…

We study subgraphs that appear in large Ramsey graphs for a given graph $F$. The recent girth Ramsey theorem of the first two authors asserts that there are Ramsey graphs such that all small subgraphs are `forests of copies of $F$'…

Combinatorics · Mathematics 2025-02-17 Christian Reiher , Vojtěch Rödl , Mathias Schacht

An $({\cal I},{\cal F}_d)$-partition of a graph is a partition of the vertices of the graph into two sets $I$ and $F$, such that $I$ is an independent set and $F$ induces a forest of maximum degree at most $d$. We show that for all $M<3$…

Discrete Mathematics · Computer Science 2016-06-15 François Dross , Mickael Montassier , Alexandre Pinlou

For each integer k >= 2, we determine a sharp bound on mad(G) such that V(G) can be partitioned into sets I and F_k, where I is an independent set and G[F_k] is a forest in which each component has at most k vertices. For each k we…

Combinatorics · Mathematics 2021-10-06 Daniel W. Cranston , Matthew P. Yancey