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AT-free graphs are characterized by vertex elimination orders. We show that these AT-free orders of a graph can be generated in constant amortized time.

Combinatorics · Mathematics 2021-08-20 Jou-Ming Chang , Ton Kloks , Hung-Lung Wang

We develop a linear time algorithm for finding the diameter of an asteroidal triple-free (AT-free) graph. Furthermore, we update the definition of polar pairs and develop new properties of polar pairs for (weak) dominating pair graphs. We…

Data Structures and Algorithms · Computer Science 2023-03-24 Oleksiy Al-saadi , Jitender Deogun

A graph algorithm is truly subquadratic if it runs in ${\cal O}(m^b)$ time on connected $m$-edge graphs, for some positive $b < 2$. Roditty and Vassilevska Williams (STOC'13) proved that under plausible complexity assumptions, there is no…

Data Structures and Algorithms · Computer Science 2020-10-30 Guillaume Ducoffe

Lexicographic Breadth First Search (LBFS) is one of fundamental graph search algorithms that has numerous applications, including recognition of graph classes, computation of graph parameters, and detection of certain graph structures. The…

Discrete Mathematics · Computer Science 2015-09-07 Jan Gorzny , Jing Huang

Let F be a set of ordered patterns, i.e., graphs whose vertices are linearly ordered. An F-free ordering of the vertices of a graph H is a linear ordering of V(H) such that none of patterns in F occurs as an induced ordered subgraph. We…

Discrete Mathematics · Computer Science 2014-08-08 Pavol Hell , Bojan Mohar , Arash Rafiey

An \emph{asteroidal triple} is a set of three independent vertices in a graph such that any two vertices in the set are connected by a path which avoids the neighbourhood of the third. A classical result by Lekkerkerker and Boland \cite{6}…

Discrete Mathematics · Computer Science 2015-05-29 Lalla Mouatadid , Robert Robere

In an attempt to understanding the complexity of the independent set problem, Chv{\'a}tal defined t-perfect graphs. While a full characterization of this class is still at large, progress has been achieved for claw-free graphs [Bruhn and…

Discrete Mathematics · Computer Science 2022-11-08 Yixin Cao , Shenghua Wang

A hole is a chordless cycle with at least four vertices. A hole is odd if it has an odd number of vertices. A dart is a graph which vertices $a, b, c, d, e$ and edges $ab, bc, bd, be, cd, de$. Dart-free graphs have been actively studied in…

Combinatorics · Mathematics 2025-04-30 Chính T. Hoàng

An asteroidal triple is a stable set of three vertices such that each pair is connected by a path avoiding the neighborhood of the third vertex. Asteroidal triples play a central role in a classical characterization of interval graphs by…

Discrete Mathematics · Computer Science 2008-12-30 Kathie Cameron , Chinh Hoàng , Benjamin Lévêque

We give an exact characterization of 3-colorability of triangle-free graphs drawn in the torus, in the form of 186 "templates" (graphs with certain faces filled by arbitrary quadrangulations) such that a graph from this class is not…

Combinatorics · Mathematics 2020-09-03 Zdeněk Dvořák , Jakub Pekárek

We consider the problem of estimating undirected triangle-free graphs of high dimensional distributions. Triangle-free graphs form a rich graph family which allows arbitrary loopy structures but 3-cliques. For inferential tractability, we…

Machine Learning · Statistics 2015-04-24 Junwei Lu , Han Liu

Given a set $F$ of oriented graphs, a graph $G$ is an $F$-graph if it admits an $F$-free orientation. Building on previous work by Bang-Jensen and Urrutia, we propose a master algorithm that determines if a graph admits an $F$-free…

Combinatorics · Mathematics 2023-01-16 Santiago Guzmán-Pro , César Hernández-Cruz

A graph is probe diamond-free if its vertex set admits a partition into probes and nonprobes, where the set of nonprobes is independent, such that adding edges only between pairs of nonprobes yields a diamond-free graph. Although this class…

Combinatorics · Mathematics 2026-05-19 Luciano Norberto Grippo Min Chih Lin

A graph is called t-perfect if its stable set polytope is defined by non-negativity, edge and odd-cycle inequalities. We show that it can be decided in polynomial time whether a given claw-free graph is t-perfect.

Discrete Mathematics · Computer Science 2013-10-31 Henning Bruhn , Oliver Schaudt

A triangle-free graph G is called k-existentially complete if for every induced k-vertex subgraph H of G, every extension of H to a (k+1)-vertex triangle-free graph can be realized by adding another vertex of G to H. Cherlin asked whether…

Combinatorics · Mathematics 2015-08-13 Chaim Even-Zohar , Nati Linial

We study convexity properties of graphs. In this paper we present a linear-time algorithm for the geodetic number in tree-cographs. Settling a 10-year-old conjecture, we prove that the Steiner number is at least the geodetic number in…

Discrete Mathematics · Computer Science 2015-09-17 Wing-Kai Hon , Ton Kloks , Hsiang-Hsuan Liu , Hung-Lung Wang , Yue-Li Wang

We consider the triangle-free process: given an integer n, start by taking a uniformly random ordering of the edges of the complete n-vertex graph K_n. Then, traverse the ordered edges and add each traversed edge to an (initially empty)…

Combinatorics · Mathematics 2009-07-06 Guy Wolfovitz

Since planar triangle-free graphs are 3-colourable, such a graph with n vertices has an independent set of size at least n/3. We prove that unless the graph contains a certain obstruction, its independence number is at least n/(3-epsilon)…

Combinatorics · Mathematics 2017-02-10 Zdeněk Dvořák , Jordan Venters

Consider the triangle-free graph process, which starts from the empty graph on $n$ vertices and a random ordering of the possible ${n \choose 2}$ edges; the edges are added in this ordering provided the graph remains triangle free. We will…

Combinatorics · Mathematics 2010-02-12 Stefanie Gerke , Tamás Makai

The Dichotomy Conjecture for constraint satisfaction problems has been verified for conservative problems (or, equivalently, for list homomorphism problems) by Andrei Bulatov. An earlier case of this dichotomy, for list homomorphisms to…

Computational Complexity · Computer Science 2010-04-21 Pavol Hell , Arash Rafiey
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