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The analysis of signals defined over a graph is relevant in many applications, such as social and economic networks, big data or biological networks, and so on. A key tool for analyzing these signals is the so called Graph Fourier Transform…

Spectral Theory · Mathematics 2017-10-11 Stefania Sardellitti , Sergio Barbarossa , Paolo Di Lorenzo

Let $G$ be a connected general graph of even order, with a function $f\colon V(G)\to\Z^+$. We obtain that $G$ satisfies the Tutte's condition \[ o(G-S)\le \sum_{v\in S}f(v)\qquad\text{for any nonempty set $S\subset V(G)$}, \] with respect…

Combinatorics · Mathematics 2018-06-26 Hongliang Lu , David G. L. Wang

Let $G$ be a graph, and $g,f:V(G)\rightarrow N$ be two functions with $g(x)\leq f(x)$ for each vertex $x$ in $G$. We say that $G$ has all fractional $(g,f)$-factors if $G$ includes a fractional $r$-factor for every $r:V(G)\rightarrow N$…

Combinatorics · Mathematics 2014-12-15 Zhiren Sun , Sizhong Zhou

It is well known that if $G = (V, E)$} is a multigraph and $X\subset V$ is a subset of even order, then $G$ contains a spanning forest $H$ such that each vertex from $X$ has an odd degree in $H$ and all the other vertices have an even…

Combinatorics · Mathematics 2020-04-29 Csilla Bujtás , Stanislav Jendrol , Zsolt Tuza

A 2-factor of a graph $G$ is a 2-regular spanning subgraph of $G$. We present a survey summarising results on the structure of 2-factors in regular graphs, as achieved by various researchers in recent years.

Combinatorics · Mathematics 2024-08-16 D. Labbate , F. Romaniello

Dujmovi\'c et al (FOCS2019) recently proved that every planar graph $G$ is a subgraph of $H\boxtimes P$, where $\boxtimes$ denotes the strong graph product, $H$ is a graph of treewidth 8 and $P$ is a path. This result has found numerous…

Data Structures and Algorithms · Computer Science 2020-12-15 Pat Morin

Let $H$ be a fixed graph on $v$ vertices. For an $n$-vertex graph $G$ with $n$ divisible by $v$, an $H$-{\em factor} of $G$ is a collection of $n/v$ copies of $H$ whose vertex sets partition $V(G)$. In this paper we consider the threshold…

Combinatorics · Mathematics 2008-03-25 A. Johansson , J. Kahn , V. Vu

A graph $G$ is $[a,b]$-covered if for each edge $e$ of $G$ there is an $[a,b]$-factor containing it. For $a=b=1$, an $[a,b]$-covered graph is a matching covered graph. The structural theory of matching covered graphs constitutes a…

Combinatorics · Mathematics 2026-05-07 Qixuan Yuan , Ruifang Liu , Jinjiang Yuan

A {\it star-factor} of a graph $G$ is a spanning subgraph of $G$ such that each of its component is a star. Clearly, every graph without isolated vertices has a star factor. A graph $G$ is called {\it star-uniform} if all star-factors of…

Combinatorics · Mathematics 2007-07-03 Mikio Kano , Yunjian Wu , Qinglin Yu

We call a set $\mathcal S$ of graphs an "even subdivison-factor" of a cubic graph $G$ if $G$ contains a spanning subgraph $H$ such that every component of $H$ has an even number of vertices and is a subdivision of an element of $\mathcal…

Combinatorics · Mathematics 2012-11-12 Arthur Hoffmann-Ostenhof

For a (possibly infinite) fixed family of graphs F, we say that a graph G overlays F on a hypergraph H if V(H) is equal to V(G) and the subgraph of G induced by every hyperedge of H contains some member of F as a spanning subgraph.While it…

Data Structures and Algorithms · Computer Science 2017-03-16 Nathann Cohen , Frédéric Havet , Dorian Mazauric , Ignasi Sau , Rémi Watrigant

Given a fixed small graph H and a larger graph G, an H-factor is a collection of vertex-disjoint subgraphs $H'\subset G$, each isomorphic to H, that cover the vertices of G. If G is the complete graph $K_n$ equipped with independent U(0,1)…

Combinatorics · Mathematics 2025-02-19 Lorenzo Federico , Joel Larsson Danielsson

Let $H$ be a fixed undirected graph on $k$ vertices. The $H$-hitting set problem asks for deleting a minimum number of vertices from a given graph $G$ in such a way that the resulting graph has no copies of $H$ as a subgraph. This problem…

Data Structures and Algorithms · Computer Science 2020-12-01 Noah Brüstle , Tal Elbaz , Hamed Hatami , Onur Kocer , Bingchan Ma

In this paper, we relate a beautiful theory by Lov\'asz with a popular heuristic algorithm for the graph isomorphism problem, namely the color refinement algorithm and its k-dimensional generalization known as the Weisfeiler-Leman…

Data Structures and Algorithms · Computer Science 2018-05-23 Holger Dell , Martin Grohe , Gaurav Rattan

Interaction between clique number $\omega(G) $ and chromatic number $\chi(G) $ of a graph is a well studied topic in graph theory. Perfect Graph Theorems are probably the most important results in this direction. Graph $G$ is called…

Logic in Computer Science · Computer Science 2018-12-31 Abhishek Kr Singh , Raja Natarajan

Given $k\ge 2$ and two $k$-graphs ($k$-uniform hypergraphs) $F$ and $H$, an $F$-factor in $H$ is a set of vertex-disjoint copies of $F$ that together covers the vertex set of $H$. Lenz and Mubayi [J. Combin. Theory Ser. B, 2016] studied the…

Combinatorics · Mathematics 2022-03-16 Laihao Ding , Jie Han , Shumin Sun , Guanghui Wang , Wenling Zhou

A homomorphism from a graph $G$ to a graph $H$ is an edge-preserving mapping from $V(G)$ to $V(H)$. For a fixed graph $H$, in the list homomorphism problem, denoted by LHom($H$), we are given a graph $G$, whose every vertex $v$ is equipped…

Computational Complexity · Computer Science 2022-02-04 Karolina Okrasa , Paweł Rzążewski

We introduce a series of graph decompositions based on the modulator/target scheme of modification problems that enable several algorithmic applications that parametrically extend the algorithmic potential of planarity. In the core of our…

Data Structures and Algorithms · Computer Science 2025-10-17 Fedor V. Fomin , Petr A. Golovach , Laure Morelle , Dimitrios M. Thilikos

The Perfect Graph Theorems are important results in graph theory describing the relationship between clique number $\omega(G) $ and chromatic number $\chi(G) $ of a graph $G$. A graph $G$ is called \emph{perfect} if $\chi(H)=\omega(H)$ for…

Logic in Computer Science · Computer Science 2019-12-06 Abhishek Kr Singh , Raja Natarajan

We say that a graph G has a perfect H-packing (also called an H-factor) if there exists a set of disjoint copies of H in G which together cover all the vertices of G. Given a graph H, we determine, asymptotically, the Ore-type degree…

Combinatorics · Mathematics 2009-06-02 Daniela Kühn , Deryk Osthus , Andrew Treglown