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We study graphs whose chromatic number is close to the order of the graph (the number of vertices). Both when the chromatic number is a constant multiple of the order and when the difference of the chromatic number and the order is a small…

Combinatorics · Mathematics 2011-07-14 Csaba Biró

Online Contention Resolution Schemes (OCRS's) represent a modern tool for selecting a subset of elements, subject to resource constraints, when the elements are presented to the algorithm sequentially. OCRS's have led to some of the…

Data Structures and Algorithms · Computer Science 2024-04-03 Calum MacRury , Will Ma , Nathaniel Grammel

For a graph with edge ordering, a linear order on the edge set, we obtain a permutation of vertices by considering the edges as transpositions of endvertices. It is known from D\'enes' results that the permutation of a tree is a full cyclic…

Combinatorics · Mathematics 2023-05-31 Ryo Uchiumi

In some applications of matching, the structural or hierarchical properties of the two graphs being aligned must be maintained. The hierarchical properties are induced by the direction of the edges in the two directed graphs. These…

Data Structures and Algorithms · Computer Science 2009-09-29 Sean M. Falconer , Dmitri Maslov

This paper considers two important questions in the well-studied theory of graphs that are $F$-saturated. A graph $G$ is called $F$-saturated if $G$ does not contain a subgraph isomorphic to $F$, but the addition of any edge creates a copy…

Combinatorics · Mathematics 2020-07-17 Debsoumya Chakraborti , Po-Shen Loh

Let $G=(V,E)$ be a graph without isolated vertices. A set $S\subseteq V$ is a paired-domination set if every vertex in $V-S$ is adjacent to a vertex in $S$ and the subgraph induced by $S$ contains a perfect matching. The paired-domination…

Combinatorics · Mathematics 2008-02-21 Lei Chen Changhong Lu Zhenbing Zeng

Path cover is a well-known intractable problem that finds a minimum number of vertex disjoint paths in a given graph to cover all the vertices. We show that a variant, where the objective function is not the number of paths but the number…

Data Structures and Algorithms · Computer Science 2018-03-09 Yinhui Cai , Guangting Chen , Yong Chen , Randy Goebel , Guohui Lin , Longcheng Liu , An Zhang

Efficiently solving the Job Shop Scheduling Problem in real-world industrial applications requires policies that are both computationally lean and topologically robust. While Reinforcement Learning has shown potential in automating…

Machine Learning · Computer Science 2026-04-28 Jonathan Hoss , Moritz Link , Noah Klarmann

We study the class of 1-perfectly orientable graphs, that is, graphs having an orientation in which every out-neighborhood induces a tournament. 1-perfectly orientable graphs form a common generalization of chordal graphs and circular arc…

Combinatorics · Mathematics 2016-03-08 Tatiana Romina Hartinger , Martin Milanič

We consider the problem of finding a Hamiltonian path or a Hamiltonian cycle with precedence constraints in the form of a partial order on the vertex set. We show that the path problem is $\mathsf{NP}$-complete for graphs of pathwidth 4…

Discrete Mathematics · Computer Science 2025-07-01 Jesse Beisegel , Katharina Klost , Kristin Knorr , Fabienne Ratajczak , Robert Scheffler

This paper addresses the problem of synchronizing orthogonal matrices over directed graphs. For synchronized transformations (or matrices), composite transformations over loops equal the identity. We formulate the synchronization problem as…

Optimization and Control · Mathematics 2017-04-10 Johan Thunberg , Florian Bernard , Jorge Goncalves

Equality saturation, a technique for program optimisation and reasoning, has gained attention due to the resurgence of equality graphs (e-graphs). E-graphs represent equivalence classes of terms under rewrite rules, enabling simultaneous…

Logic in Computer Science · Computer Science 2025-05-05 Aleksei Tiurin , Dan R. Ghica , Nick Hu

We consider a bipartite version of the color degree matrix problem. A bipartite graph $G(U,V,E)$ is half-regular if all vertices in $U$ have the same degree. We give necessary and sufficient conditions for a bipartite degree matrix (also…

Combinatorics · Mathematics 2016-02-16 Mark Aksen , Istvan Miklos , Kathleen Zhou

As a fundamental problem in pattern recognition, graph matching has applications in a variety of fields, from computer vision to computational biology. In graph matching, patterns are modeled as graphs and pattern recognition amounts to…

Computer Vision and Pattern Recognition · Computer Science 2008-06-19 Tiberio S. Caetano , Julian J. McAuley , Li Cheng , Quoc V. Le , Alex J. Smola

Motivated by Keisler's order, a far-reaching program of understanding basic model-theoretic structure through the lens of regular ultrapowers, we prove that for a class of regular filters $D$ on $I$, $|I| = \lambda > \aleph_0$, the fact…

Logic · Mathematics 2012-08-29 M. Malliaris , S. Shelah

An {\em ordered $r$-graph} is an $r$-uniform hypergraph whose vertex set is linearly ordered. Given $2\leq k\leq r$, an ordered $r$-graph $H$ is {\em interval} $k$-{\em partite} if there exist at least $k$ disjoint intervals in the ordering…

Combinatorics · Mathematics 2020-04-13 Zoltán F\" uredi , Tao Jiang , Alexandr Kostochka , Dhruv Mubayi , Jacques Verstraëte

Multicriteria Decision Making problems are important both for individuals and groups. Pairwise comparisons have become popular in the theory and practice of preference modelling and quantification. We focus on decision problems where the…

Discrete Mathematics · Computer Science 2025-09-04 Sándor Bozóki , Zsombor Szádoczki , Hailemariam Abebe Tekile

A theorem of Ding, Oporowski, Oxley, and Vertigan implies that any sufficiently large twin-free graph contains a large matching, a co-matching, or a half-graph as a semi-induced subgraph. The sizes of these unavoidable patterns are measured…

Computational Complexity · Computer Science 2026-02-10 Jan Dreier , Nikolas Mählmann , Sebastian Siebertz

In the Minimum Clique Routing Problem on Cycles \textsc{MCRPC} we are given a cycle together with a set of demands (weighted origin-destination pairs) and the goal is to route all the pairs minimizing the maximum weighted clique of the…

Data Structures and Algorithms · Computer Science 2023-11-17 Mariana Escalante , Martín Matamala , Iván Rapaport , Paola Tolomei , Luis Miguel Torres

We prove that every infinite sequence of skew-symmetric or symmetric matrices M_1, M_2, ... over a fixed finite field must have a pair M_i, M_j (i<j) such that M_i is isomorphic to a principal submatrix of the Schur complement of a…

Combinatorics · Mathematics 2014-03-26 Sang-il Oum