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We introduce the Orchard crossing number, which is defined in a similar way to the well-known rectilinear crossing number. We compute the Orchard crossing number for some simple families of graphs. We also prove some properties of this…

Combinatorics · Mathematics 2009-04-23 Elie Feder , David Garber

We compute the Orchard crossing number, which is defined in a similar way to the rectilinear crossing number, for the complete bipartite graphs K_{n,n}.

Combinatorics · Mathematics 2010-08-17 Elie Feder , David Garber

There has been significant research dedicated towards computing the crossing numbers of families of graphs resulting from the Cartesian products of small graphs with arbitrarily large paths, cycles and stars. For graphs with four or fewer…

Combinatorics · Mathematics 2021-06-08 Kieran Clancy , Michael Haythorpe , Alex Newcombe

The simple connected graphs may be classified by their cycle composition (number and lengths of cycles). This work derives the counting series of the simple connected graphs that have cycles of unrestricted number and length, but no…

Combinatorics · Mathematics 2018-08-21 Richard J. Mathar

We call an oriented odd cycle alternating if it has exactly one vertex whose in-degree and out-degree are both positive. In this paper, we investigate whether certain graphs admit an orientation that avoids alternating odd cycles as…

Combinatorics · Mathematics 2025-08-27 Nóra Almási , Gábor Simonyi

In this paper we provide some sufficient conditions for the existence of an odd or even cycle that passing a given vertex or an edge in $2$-connected or $2$-edge connected graphs. We provide some similar conditions for the existence of an…

Discrete Mathematics · Computer Science 2015-12-09 Saieed Akbari , Khashayar Etemadi , Peyman Ezzati , Mehrdad Ghadiri

We present, to the best of the authors' knowledge, all known results for the (planar) crossing numbers of specific graphs and graph families. The results are separated into various categories; specifically, results for general graph…

Combinatorics · Mathematics 2021-12-09 Kieran Clancy , Michael Haythorpe , Alex Newcombe

We prove that, for the edge ideal of a graph whose cycles are pairwise vertex-disjoint, the arithmetical rank is bounded above by the sum of the number of cycles and the maximum height of its associated primes.

Commutative Algebra · Mathematics 2015-11-24 Margherita Barile , Antonio Macchia

A cycle in a graph is called dominating if every edge of the graph is incident with a vertex of the cycle. In this paper, we investigate forbidden pairs guaranteeing the existence of a dominating cycle in 2-connected graphs.

Combinatorics · Mathematics 2015-02-10 Shuya Chiba , Michitaka Furuya , Shoichi Tsuchiya

The edges surrounding a face of a map $M$ form a cycle $C$, called the boundary cycle of the face, and $C$ is often not a simple cycle. If the map $M$ is arc-transitive, then there is a cyclic subgroup of automorphisms of $M$ which leaves…

Combinatorics · Mathematics 2021-11-05 Jiyong Chen , Cai Heng Li , Cheryl E. Praeger , Shu-Jiao Song

Let $S$ be a set of $n$ points in the plane in general position. Two line segments connecting pairs of points of $S$ cross if they have an interior point in common. Two vertex disjoint geometric graphs with vertices in $S$ cross if there…

In this note, we describe a construction that leads to families of graphs whose critical groups are cyclic. For some of these families we are able to give a formula for the number of spanning trees of the graph, which then determines the…

Combinatorics · Mathematics 2015-04-23 Ryan Becker , Darren Glass

Dirac and Lov\'{a}sz independently characterized the $3$-connected graphs with no pair of vertex-disjoint cycles. Equivalently, they characterized all $3$-connected graphs with no prism-minors. In this paper, we completely characterize the…

Combinatorics · Mathematics 2021-01-14 João Paulo Costalonga , Talmage James Reid , Haindong Wu

The class of closed graphs by a linear ordering on their sets of vertices is investigated. A recent characterization of such a class of graphs is analyzed by using tools from the proper interval graph theory.

Combinatorics · Mathematics 2015-09-23 Marilena Crupi

A geometric graph is a graph whose vertices are points in general position in the plane and its edges are straight line segments joining these points. In this paper we give an $O(n^2 \log n)$ algorithm to compute the number of pairs of…

Computational Geometry · Computer Science 2020-09-04 Frank Duque , Ruy Fabila-Monroy , César Hernández-Vélez , Carlos Hidalgo-Toscano

An arithmetical structure on a graph is given by a labeling of the vertices which satisfies certain divisibility properties. In this note, we look at several families of graphs and attempt to give counts on the number of arithmetical…

Combinatorics · Mathematics 2019-03-05 Darren Glass , Joshua Wagner

In general graph theory, the only relationship between vertices are expressed via the edges. When the vertices are embedded in an Euclidean space, the geometric relationships between vertices and edges can be interesting objects of study.…

Combinatorics · Mathematics 2017-02-28 Chai Wah Wu

We show a generalization of the crossing lemma for multi-graphs drawn on orientable surfaces in which pairs of edges are assumed to be drawn by non-homotopic simple arcs which pairwise cross at most $k$ times.

Combinatorics · Mathematics 2025-06-24 Alfredo Hubard , Hugo Parlier

We introduce the cycle intersection graph of a graph, an adaptation of the cycle graph of a graph, and use the structure of these graphs to prove an upper bound for the decycling number of all even graphs. This bound is shown to be…

Combinatorics · Mathematics 2018-10-11 Michael Cary

A geometric graph is a graph drawn in the plane with vertices represented by points and edges as straight-line segments. A geometric graph contains a (k,l)-crossing family if there is a pair of edge subsets E_1,E_2 such that |E_1| = k and…

Combinatorics · Mathematics 2011-03-28 Radoslav Fulek , Andrew Suk
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