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In this paper, we continue the study of the total domination game in graphs introduced in [Graphs Combin. 31(5) (2015), 1453--1462], where the players Dominator and Staller alternately select vertices of $G$. Each vertex chosen must…

Combinatorics · Mathematics 2015-12-10 Michael A. Henning , Douglas F. Rall

Let $\ell$ be a rational prime. We show that an analogue of a conjecture of Greenberg in graph theory holds true. More precisely, we show that when $n$ is sufficiently large, the $\ell$-adic valuation of the number of spanning trees at the…

Combinatorics · Mathematics 2022-07-06 Sage DuBose , Daniel Vallières

The Merino-Welsh conjecture asserts that the number of spanning trees of a graph is no greater than the maximum of the numbers of totally cyclic orientations and acyclic orientations of that graph. We prove this conjecture for the class of…

Combinatorics · Mathematics 2013-03-27 Steven D. Noble , Gordon F. Royle

We establish maximal trees and graphs for the difference of average distance and proximity proving thus the corresponding conjecture posed in [4]. We also establish maximal trees for the difference of average eccentricity and remoteness and…

Combinatorics · Mathematics 2020-10-22 Jelena Sedlar

Vertex deletion and edge deletion problems play a central role in Parameterized Complexity. Examples include classical problems like Feedback Vertex Set, Odd Cycle Transversal, and Chordal Deletion. Interestingly, the study of edge…

Data Structures and Algorithms · Computer Science 2011-04-20 Pinar Heggernes , Pim van 't Hof , Benjamin Lévêque , Daniel Lokshtanov , Christophe Paul

A path cover is a decomposition of the edges of a graph into edge-disjoint simple paths. Gallai conjectured that every connected $n$-vertex graph has a path cover with at most $\lceil n/2 \rceil$ paths. We prove Gallai's conjecture for…

Combinatorics · Mathematics 2017-06-14 Philipp Kindermann , Lena Schlipf , André Schulz

We consider the problem of exploring an unknown tree with a team of $k$ initially colocated mobile agents. Each agent has limited energy and cannot, as a result, traverse more than $B$ edges. The goal is to maximize the number of nodes…

Data Structures and Algorithms · Computer Science 2018-02-20 Evangelos Bampas , Jérémie Chalopin , Shantanu Das , Jan Hackfeld , Christina Karousatou

A simple graph more often than not contains adjacent vertices with equal degrees. This in particular holds for all pairs of neighbours in regular graphs, while a lot such pairs can be expected e.g. in many random models. Is there a…

Combinatorics · Mathematics 2020-03-31 Jakub Przybyło

Graph burning is a discrete-time process that models the spread of influence in a network. Vertices are either burning or unburned, and in each round, a burning vertex causes all of its neighbours to become burning before a new fire source…

Combinatorics · Mathematics 2024-09-24 Karen Gunderson , William Kellough , JD Nir , Hritik Punj

A branch vertex in a tree is a vertex of degree at least three. We prove that, for all $s\geq 1$, every connected graph on $n$ vertices with minimum degree at least $(\frac{1}{s+3}+o(1))n$ contains a spanning tree having at most $s$ branch…

Combinatorics · Mathematics 2019-10-10 Louis DeBiasio , Allan Lo

The equitable tree-coloring can formulate a structure decomposition problem on the communication network with some security considerations. Namely, an equitable tree-$k$-coloring of a graph is a vertex coloring using $k$ distinct colors…

Combinatorics · Mathematics 2021-04-13 Xin Zhang , Bei Niu , Yan Li , Bi Li

This work gives the first natural non-utilitarian problems for which the trivial $n$ approximation via VCG mechanisms is the best possible. That is, no truthful mechanism can be better than $n$ approximate, where $n$ is the number of…

Computer Science and Game Theory · Computer Science 2018-05-31 Stefano Leucci , Akaki Mamageishvili , Paolo Penna

In this work, we introduce graphical modelsfor multi-player game theory, and give powerful algorithms for computing their Nash equilibria in certain cases. An n-player game is given by an undirected graph on n nodes and a set of n local…

Computer Science and Game Theory · Computer Science 2015-03-10 Michael Kearns , Michael L. Littman , Satinder Singh

Consider an undirected graph modeling a social network, where the vertices represent users, and the edges do connections among them. In the competitive diffusion game, each of a number of players chooses a vertex as a seed to propagate…

Computational Complexity · Computer Science 2014-12-11 Takehiro Ito , Yota Otachi , Toshiki Saitoh , Hisayuki Satoh , Akira Suzuki , Kei Uchizawa , Ryuhei Uehara , Katsuhisa Yamanaka , Xiao Zhou

We propose the conjecture that every graph $G$ of order $n$ with less than $3n-6$ edges has a vertex cut that induces a forest. Maximal planar graphs do not have such vertex cuts and show that the density condition would be best possible.…

Combinatorics · Mathematics 2024-09-27 Vsevolod Chernyshev , Johannes Rauch , Dieter Rautenbach

An independent set in a graph $G$ is a set of pairwise non-adjacent vertices. A tree decomposition of $G$ is a pair $(T, \chi)$ where $T$ is a tree and $\chi : V(T) \rightarrow 2^{V(G)}$ is a function satisfying the following two axioms:…

Combinatorics · Mathematics 2026-05-07 Maria Chudnovsky , Ajaykrishnan E S , Daniel Lokshtanov

We study a cooperative game in which each member of a team of $N$ players, wearing coloured hats and situated at the vertices of a cycle graph $C_N$, is guessing their own hat colour merely on the basis of observing the hats worn by their…

Combinatorics · Mathematics 2015-05-01 Witold W. Szczechla

Consider a rooted Galton-Watson tree $T$, to each of whose edges we assign, independently, a weight that equals $+1$ with probability $p_{1}$, $0$ with probability $p_{0}$ and $-1$ with probability $p_{-1}=1-p_{1}-p_{0}$. We play a game on…

Probability · Mathematics 2025-01-16 Sayar Karmakar , Moumanti Podder , Souvik Roy , Soumyarup Sadhukhan

We consider how selfish agents are likely to share revenues derived from maintaining connectivity between important network servers. We model a network where a failure of one node may disrupt communication between other nodes as a…

Computer Science and Game Theory · Computer Science 2014-02-05 Yoram Bachrach , Ely Porat Porat , Jeffrey S. Rosenschein

A graph $G$ of order $n$ is said to be a sum basic equilibrium if and only if for every edge $uv$ from $G$ and any node $v'$ from $G$, when performing the swap of the edge $uv$ for the edge $uv'$, the sum of the distances from $u$ to all…

Combinatorics · Mathematics 2023-04-26 Aida Abiad , Carme Alvarez , Arnau Messegué