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Multiple interval graphs are a well-known generalization of interval graphs introduced in the 1970s to deal with situations arising naturally in scheduling and allocation. A $d$-interval is the union of $d$ intervals on the real line, and a…

Computational Complexity · Computer Science 2023-09-22 Virginia Ardévol Martínez , Romeo Rizzi , Florian Sikora , Stéphane Vialette

We unify several seemingly different graph and digraph classes under one umbrella. These classes are all broadly speaking different generalizations of interval graphs, and include, in addition to interval graphs, also adjusted interval…

Discrete Mathematics · Computer Science 2018-06-28 Pavol Hell , Jing Huang , Ross M. McConnell , Arash Rafiey

The distinguishing number $D(G)$ of a graph $G$ is the least integer $d$ such that $G$ has a vertex labeling with $d$ labels that is preserved only by a trivial automorphism. We say that a graph $G$ is $d$-distinguishing critical, if…

Combinatorics · Mathematics 2017-12-05 Saeid Alikhani , Samaneh Soltani

We introduce and investigate generalizations of interval and proper interval graphs to simplicial complexes, including strong interval, unit interval, and under closed variants. Through equivalent combinatorial and algebraic…

Combinatorics · Mathematics 2025-10-21 Fahimeh Khosh-Ahang Ghasr

In 1969, Roberts introduced proper and unit interval graphs and proved that these classes are equal. Natural generalizations of unit interval graphs called $k$-length interval graphs were considered in which the number of different lengths…

Discrete Mathematics · Computer Science 2017-04-13 Pavel Klavík , Yota Otachi , Jiří Šejnoha

The class of 2-interval graphs has been introduced for modelling scheduling and allocation problems, and more recently for specific bioinformatic problems. Some of those applications imply restrictions on the 2-interval graphs, and justify…

Discrete Mathematics · Computer Science 2008-02-04 Philippe Gambette , Stéphane Vialette

We introduce the class of interval $H$-graphs, which is the generalization of interval graphs, particularly interval bigraphs. For a fixed graph $H$ with vertices $a_1,a_2,\dots,a_k$, we say that an input graph $G$ with given partition…

Discrete Mathematics · Computer Science 2025-03-04 Haiko Müller , Arash Rafiey

A graph is $\mathcal{R}_d$-independent (resp. $\mathcal{R}_d$-connected) if its $d$-dimensional generic rigidity matroid is free (resp. connected). A result of Maxwell from 1867 implies that every $\mathcal{R}_d$-independent graph satisfies…

Combinatorics · Mathematics 2025-09-04 Dániel Garamvölgyi , Bill Jackson , Tibor Jordán

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex (edge) labeling with $d$ labels that is preserved only by the trivial automorphism. It is known that for every graph $G$…

Combinatorics · Mathematics 2017-10-24 Saeid Alikhani , Samaneh Soltani

The twin-width of a graph $G$ is the minimum integer $d$ such that $G$ has a $d$-contraction sequence, that is, a sequence of $|V(G)|-1$ iterated vertex identifications for which the overall maximum number of red edges incident to a single…

Discrete Mathematics · Computer Science 2020-06-18 Édouard Bonnet , Colin Geniet , Eun Jung Kim , Stéphan Thomassé , Rémi Watrigant

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. Let $G$ be a connected graph…

Combinatorics · Mathematics 2016-07-26 Samaneh Soltani , Saeid Alikhani

A $d$-dimensional framework is a pair $(G,p)$, where $G$ is a graph and $p$ maps the vertices of $G$ to points in $\mathbb{R}^d$. The edges of $G$ are mapped to the corresponding line segments. A graph $G$ is said to be globally rigid in…

Combinatorics · Mathematics 2024-09-12 Dániel Garamvölgyi , Tibor Jordán

The distance ideals of graphs are algebraic invariants that generalize the Smith normal form (SNF) and the spectrum of several distance matrices associated with a graph. In general, distance ideals are not monotone under taking induced…

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex (edge) labeling with $d$ labels that is preserved only by the trivial automorphism. It is known that for every graph $G$…

Combinatorics · Mathematics 2017-08-11 Saeid Alikhani , Sandi Klavžar , Florian Lehner , Samaneh Soltani

The \emph{difference subgroup graph} $D(G)$ of a finite group $G$ is defined as the graph whose vertices are the non-trivial proper subgroups of $G$, with two distinct vertices $H$ and $K$ adjacent if and only if $\langle H, K \rangle = G$…

Group Theory · Mathematics 2025-11-07 Angsuman Das , Arnab Mandal , Labani Sarkar

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. The lexicographic product of…

Combinatorics · Mathematics 2016-06-28 Saeid Alikhani , Samaneh Soltani

A graph $G$ is a $D\!D_2$-graph if it has a pair $(D,D_2)$ of disjoint sets of vertices of $G$ such that $D$ is a dominating set and $D_2$ is a 2-dominating set of $G$. We provide several characterizations and hardness results concerning…

Combinatorics · Mathematics 2019-03-15 Mateusz Miotk , Jerzy Topp , Paweł Żyliński

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. The co-normal product $G\star…

Combinatorics · Mathematics 2017-07-21 Saeid Alikhani , Samaneh Soltani

A graph is called $d$-rigid if there exists a generic embedding of its vertex set into $\mathbb{R}^d$ such that every continuous motion of the vertices that preserves the lengths of all edges actually preserves the distances between all…

Combinatorics · Mathematics 2023-12-13 Michael Krivelevich , Alan Lew , Peleg Michaeli

A $1$-factorization of a graph $G$ is a collection of edge-disjoint perfect matchings whose union is $E(G)$. A trivial necessary condition for $G$ to admit a $1$-factorization is that $|V(G)|$ is even and $G$ is regular; the converse is…

Combinatorics · Mathematics 2018-04-09 Asaf Ferber , Vishesh Jain
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