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Let $G \leq \mathrm{Sym} (X)$ for a countable set $X$. Call a colouring of $X$ asymmetric, if the identity is the only element of $G$ which preserves all colours. The motion (also called minimal degree) of $G$ is the minimal number of…

Group Theory · Mathematics 2022-09-23 Florian Lehner

Arboricity is a graph parameter akin to chromatic number, in that it seeks to partition the vertices into the smallest number of sparse subgraphs. Where for the chromatic number we are partitioning the vertices into independent sets, for…

We prove upper and lower bounds on the chromatic number of the square of the cartesian product of trees. The bounds are equal if each tree has even maximum degree.

Combinatorics · Mathematics 2011-10-05 David R. Wood

A well-known result of Stanley's shows that given a graph $G$ with chromatic symmetric function expanded into the basis of elementary symmetric functions as $X_G = \sum c_{\lambda}e_{\lambda}$, the sum of the coefficients $c_{\lambda}$ for…

Combinatorics · Mathematics 2025-05-16 Logan Crew , Yongxing Zhang

We investigate which graphs H have the property that in every graph with bounded clique number and sufficiently large chromatic number, some induced subgraph is isomorphic to a subdivision of H. In an earlier paper, one of us proved that…

Combinatorics · Mathematics 2019-08-28 Alex Scott , Paul Seymour

A $k$-coloring of a graph $G$ is a partition of the set of vertices of $G$ into $k$ independent sets, which are called colors. A $k$-coloring is neighbor-locating if any two vertices belonging to the same color can be distinguished from…

Combinatorics · Mathematics 2024-05-09 Liliana Alcon , Marisa Gutierrez , Carmen Hernando , Mercè Mora , Ignacio M. Pelayo

The relationship between two important problems in tree pattern matching, the largest common subtree and the smallest common supertree problems, is established by means of simple constructions, which allow one to obtain a largest common…

Data Structures and Algorithms · Computer Science 2007-05-23 Francesc Rossello , Gabriel Valiente

Let $R$ and $B$ be two disjoint sets of points in the plane where the points of $R$ are colored red and the points of $B$ are colored blue, and let $n=|R\cup B|$. A bichromatic spanning tree is a spanning tree in the complete bipartite…

Computational Geometry · Computer Science 2016-11-08 Ahmad Biniaz , Prosenjit Bose , David Eppstein , Anil Maheshwari , Pat Morin , Michiel Smid

In this investigation we study a family of networks, called spiders, which covers a range of networks going from chains to complete graphs. These spiders are characterized by three parameters: the number of nodes in the core, the number of…

Combinatorics · Mathematics 2024-10-15 Leo Egghe , Li Li , Ronald Rousseau

The main result of this paper is the introduction of marked graphs and the marked graph polynomials ($M$-polynomial) associated with them. These polynomials can be defined via a deletion-contraction operation. These polynomials are a…

Combinatorics · Mathematics 2022-02-25 José Aliste-Prieto , Anna de Mier , Rosa Orellana , José Zamora

A transversal in a rooted tree is any set of nodes that meets every path from the root to a leaf. We let c(T,k) denote the number of transversals of size k in a rooted tree T. We define a partial order on the set of all rooted trees with n…

Combinatorics · Mathematics 2013-08-20 Victor Campos , Vasek Chvatal , Luc Devroye , Perouz Taslakian

We say a proper coloring of a graph is distance-$k$ fall if every vertex is within distance $k$ of at least one vertex of every color. We show that if $G$ is a connected graph of order at least $3$ that is $3$-colorable, thenit has a…

Combinatorics · Mathematics 2025-09-01 Wayne Goddard , Sonwabile Mafunda

In this paper, we refer to a asymptotic degree sequence as $\mathscr{D}=(d_1,d_2,\dots,d_n)$. The examination of topological indices on trees gives us a general overview through bounds to find the maximum and minimum bounds which reflect…

Combinatorics · Mathematics 2025-12-16 Jasem Hamoud , Duaa Abdullah

We study the chromatic symmetric function on graphs, and show that its kernel is spanned by the modular relations. We generalize this result to the chromatic quasisymmetric function on hypergraphic polytopes, a family of generalized…

Combinatorics · Mathematics 2020-03-31 Raul Penaguiao

Consider the following game. We are given a tree $T$ and two players (say) Alice and Bob who alternately colour an edge of a tree (using one of $k$ colours). If all edges of the tree get coloured, then Alice wins else Bob wins. Game…

Data Structures and Algorithms · Computer Science 2020-02-11 Akshay Singh , Sanjeev Saxena

A distinguishing index of a (di)graph is the minimum number of colours in an edge (or arc) colouring such that the identity is the only automorphism that preserves that colouring. We investigate the minimum and maximum value of the…

Combinatorics · Mathematics 2024-02-27 Aleksandra Gorzkowska , Jakub Kwaśny

A vertex colouring of a graph is called asymmetric if the only automorphism which preserves it is the identity. Tucker conjectured that if every automorphism of a connected, locally finite graph moves infinitely many vertices, then there is…

Combinatorics · Mathematics 2020-07-21 Florian Lehner , Monika Pilśniak , Marcin Stawiski

We prove that for every tree $T$ which is not an edge, for almost every graph $G$ which does not contain $T$ as an induced subgraph, $V(G)$ has a partition into $\alpha(T)-1$ parts certifying this fact. Each part induces a graph which is…

Combinatorics · Mathematics 2025-06-03 Bruce Reed , Yelena Yuditsky

There are many concepts of signed graph coloring which are defined by assigning colors to the vertices of the graphs. These concepts usually differ in the number of self-inverse colors used. We introduce a unifying concept for this kind of…

Combinatorics · Mathematics 2022-11-07 Chiara Cappello , Eckhard Steffen

We prove that, with high probability, in every $2$-edge-colouring of the random tournament on $n$ vertices there is a monochromatic copy of every oriented tree of order $O (n / \sqrt{\log n})$. This generalises a result of the first, third…

Combinatorics · Mathematics 2020-06-03 Matija Bucic , Sven Heberle , Shoham Letzter , Benny Sudakov