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Let G be an edge weighted undirected graph. For every pair of nodes consider the shortest cycle containing these nodes in G. The cycle diameter of G is the maximum length of a cycle in this set. Let H be a directed graph obtained by…

Discrete Mathematics · Computer Science 2011-05-25 Nili Guttmann-Beck , Refael Hassin

It is proved that if $G$ is a $t$-tough graph of order $n$ and minimum degree $\delta$ with $t>1$ then either $G$ has a cycle of length at least $\min\{n,2\delta+4\}$ or $G$ is the Petersen graph.

Combinatorics · Mathematics 2012-03-19 Zh. G. Nikoghosyan

Let $G$ be a simple graph. Consider all weightings of the vertices of $G$ with real numbers whose total sum is nonnegative. How many edges of $G$ have endpoints with a nonnegative sum? We consider the minimum number of such edges over all…

Combinatorics · Mathematics 2018-08-20 Zoltán Király , Neeraja Kulkarni , Ian McMeeking , Joshua Mundinger

We consider random sub-graphs of a fixed graph $G=(V,E)$ with large minimum degree. We fix a positive integer $k$ and let $G_k$ be the random sub-graph where each $v\in V$ independently chooses $k$ random neighbors, making $kn$ edges in…

Combinatorics · Mathematics 2014-05-12 Alan Frieze , Tony Johansson

Given an undirected graph $G=(V,E)$ and vertices $s,t,w_1,w_2\in V$, we study finding whether there exists a simple path $P$ from $s$ to $t$ such that $w_1,w_2 \in P$. As a sub-problem, we study the question: given an undirected graph and…

Combinatorics · Mathematics 2023-02-21 Yefim Dinitz , Solomon Eyal Shimony

For a graph $G$, let $c_k(G)$ be the number of spanning trees of $G$ with maximum degree at most $k$. For $k \ge 3$, it is proved that every connected $n$-vertex $r$-regular graph $G$ with $r \ge \frac{n}{k+1}$ satisfies $$ c_k(G)^{1/n} \ge…

Combinatorics · Mathematics 2022-08-01 Raphael Yuster

An immersion of a graph $H$ into a graph $G$ is a one-to-one mapping $f:V(H) \to V(G)$ and a collection of edge-disjoint paths in $G$, one for each edge of $H$, such that the path $P_{uv}$ corresponding to edge $uv$ has endpoints $f(u)$ and…

Combinatorics · Mathematics 2011-01-14 Matt DeVos , Zdeněk Dvořák , Jacob Fox , Jessica McDonald , Bojan Mohar , Diego Scheide

Properly colored cycles in edge-colored graphs are closely related to directed cycles in oriented graphs. As an analogy of the well-known Caccetta-H\"{a}ggkvist Conjecture, we study the existence of properly colored cycles of bounded length…

Combinatorics · Mathematics 2021-08-25 Laihao Ding , Jie Hu , Guanghui Wang , Donglei Yang

The quantum query complexity of subgraph-containment problems, which ask whether a given subgraph $H$ is present in an input graph $G$, has been the subject of considerable study. However, even for relatively simple subgraphs, such as paths…

Quantum Physics · Physics 2026-05-12 Arjan Cornelissen , Amin Shiraz Gilani , Subhasree Patro

The real minimum skew rank of a simple graph G is the smallest possible rank among all real skew symmetric matrices, whose (i,j)-entry (for i not equal to j) is nonzero whenever {i, j} is an edge in G and is zero otherwise. In this paper we…

Combinatorics · Mathematics 2011-07-14 Luz M. DeAlba , Ethan Kerzner , Sarah Tucker

We prove that any $3$-uniform hypergraph whose minimum vertex degree is at least $\left(\frac{5}{9} + o(1) \right)\binom{n}{2}$ admits an almost-spanning tight cycle, that is, a tight cycle leaving $o(n)$ vertices uncovered. The bound on…

Combinatorics · Mathematics 2016-06-20 Oliver Cooley , Richard Mycroft

A minimal counterexample to the Erd\H{o}s-Gy\'arf\'as conjecture is a graph of minimum possible order and size with minimum degree at least 3 that contains no cycle whose length is a power of 2. Markstr\"om observed that any such graph must…

Combinatorics · Mathematics 2026-05-25 Avery Carr

For an integer $k\ge 3$, a $k$-path vertex cover of a graph $G=(V,E)$ is a set $T\subseteq V$ that shares a vertex with every path subgraph of order $k$ in $G$. The minimum cardinality of a $k$-path vertex cover is denoted by $\psi_k(G)$.…

Combinatorics · Mathematics 2021-05-06 Csilla Bujtás , Marko Jakovac , Zsolt Tuza

A graph is sub-unicyclic if it contains at most one cycle. We also say that a graph $G$ is $k$-apex sub-unicyclic if it can become sub-unicyclic by removing $k$ of its vertices. We identify 29 graphs that are the minor-obstructions of the…

For a given multigraph H, a graph G is H-linked, if |G| \geq |H| and for every injective map {\tau}: V (H) \rightarrow V (G), we can find internally disjoint paths in G, such that every edge from uv in H corresponds to a {\tau} (u) - {\tau}…

Combinatorics · Mathematics 2012-06-08 Florian Pfender

We give an upper bound on the number of cycles in a simple graph in terms of its degree sequence, and apply this bound to resolve several conjectures of Kir\'aly and Arman and Tsaturian and to improve upper bounds on the maximum number of…

Combinatorics · Mathematics 2019-07-30 Zdeněk Dvořák , Natasha Morrison , Jonathan A. Noel , Sergey Norin , Luke Postle

Balogh, Csaba, Jing and Pluh\'ar recently determined the minimum degree threshold that ensures a $2$-coloured graph $G$ contains a Hamilton cycle of significant colour bias (i.e., a Hamilton cycle that contains significantly more than half…

Combinatorics · Mathematics 2021-03-05 Andrea Freschi , Joseph Hyde , Joanna Lada , Andrew Treglown

The power graph of a group $G$ is the graph whose vertex set is $G$ and two distinct vertices are adjacent if one is a power of the other. In this paper, the minimum degree of power graphs of certain classes of cyclic groups, abelian…

Combinatorics · Mathematics 2017-05-12 Ramesh Prasad Panda , K. V. Krishna

We conjecture that every oriented graph $G$ on $n$ vertices with $\delta ^+ (G) , \delta ^- (G) \geq 5n/12$ contains the square of a Hamilton cycle. We also give a conjectural bound on the minimum semidegree which ensures a perfect packing…

Combinatorics · Mathematics 2010-11-22 Andrew Treglown

The local minimum degree of a graph is the minimum degree reached by means of a series of local complementations. In this paper, we investigate on this quantity which plays an important role in quantum computation and quantum error…

Computational Complexity · Computer Science 2016-10-11 Jérôme Javelle , Mehdi Mhalla , Simon Perdrix