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A random 2-cell embedding of a given graph $G$ is obtained by choosing a random local rotation around every vertex. We analyze the expected number of faces of such an embedding, which is equivalent to studying its average genus. In 1991,…

Combinatorics · Mathematics 2023-04-03 Jesse Campion Loth , Bojan Mohar

A random 2-cell embedding of a connected graph $G$ in some orientable surface is obtained by choosing a random local rotation around each vertex. Under this setup, the number of faces or the genus of the corresponding 2-cell embedding…

Combinatorics · Mathematics 2025-04-11 Jesse Campion Loth , Kevin Halasz , Tomáš Masařík , Bojan Mohar , Robert Šámal

The $2$-cell embeddings of graphs on closed surfaces have been widely studied. It is well known that ($2$-cell) embedding a given graph $G$ on a closed orientable surface is equivalent to cyclically ordering the edges incident to each…

Combinatorics · Mathematics 2015-03-06 Ricky X. F. Chen , Christian M. Reidys

The $2$-cell embeddings of graphs on closed surfaces have been widely studied. It is well known that ($2$-cell) embedding a given graph $G$ on a closed orientable surface is equivalent to cyclically ordering the edges incident to each…

Combinatorics · Mathematics 2017-03-16 Ricky X. F. Chen , Christian M. Reidys

We approach the cycle double cover conjecture by looking for a circular 2-cell embedding of cubic graphs on an arbitrary surface. It is easy to see that if such an embedding exists, we can get to it from an arbitrary starting 2-cell…

Combinatorics · Mathematics 2026-05-05 Babak Ghanbari , Robert Šámal

A 2-cell embedding of a graph $G$ into a closed (orientable or nonorientable) surface is called regular if its automorphism group acts regularly on the flags - mutually incident vertex-edge-face triples. In this paper, we classify the…

Combinatorics · Mathematics 2010-01-19 Jin Ho Kwak , Young Soo Kwon

A "folklore conjecture, probably due to Tutte" (as described in [P.D. Seymour, Sums of circuits, Graph theory and related topics (Proc. Conf., Univ. Waterloo, 1977), pp. 341-355, Academic Press, 1979]) asserts that every bridgeless cubic…

Combinatorics · Mathematics 2011-01-14 Bojan Mohar

We study the asymptotics of large, simple, labeled graphs constrained by the densities of edges and of $k$-star subgraphs, $k\ge 2$ fixed. We prove that under such constraints graphs are "multipodal": asymptotically in the number of…

Combinatorics · Mathematics 2017-03-16 Richard Kenyon , Charles Radin , Kui Ren , Lorenzo Sadun

The inducibility of a graph $H$ measures the maximum number of induced copies of $H$ a large graph $G$ can have. Generalizing this notion, we study how many induced subgraphs of fixed order $k$ and size $\ell$ a large graph $G$ on $n$…

Combinatorics · Mathematics 2019-11-05 Noga Alon , Dan Hefetz , Michael Krivelevich , Mykhaylo Tyomkyn

We give a density condition for when, subject to a necessary parity condition, an eulerian graph or digraph may be cellularly embedded in an orientable surface so that it has exactly two faces, each bounded by an euler circuit, one of which…

Combinatorics · Mathematics 2024-09-24 M. N. Ellingham , Joanna A. Ellis-Monaghan

We investigate the joint distribution of the vertex degrees in three models of random bipartite graphs. Namely, we can choose each edge with a specified probability, choose a specified number of edges, or specify the vertex degrees in one…

Combinatorics · Mathematics 2022-12-22 Brendan D. McKay , Fiona Skerman

A digraph is 2-regular if every vertex has both indegree and outdegree two. We define an embedding of a 2-regular digraph to be a 2-cell embedding of the underlying graph in a closed surface with the added property that for every…

Combinatorics · Mathematics 2017-06-12 Dan Archdeacon , Matt DeVos , Stefan Hannie , Bojan Mohar

We prove that for every complete multipartite graph $F$ there exist very dense graphs $G_n$ on $n$ vertices, namely with as many as ${n\choose 2}-cn$ edges for all $n$, for some constant $c=c(F)$, such that $G_n$ can be decomposed into…

Combinatorics · Mathematics 2015-01-16 Csilla Bujtás , Zsolt Tuza

Given a graph $F$, the random Tur\'an problem asks to determine the maximum number of edges in an $F$-free subgraph of $G_{n,p}$. Prior to this work, the only bipartite graphs $F$ with known tight bounds included certain classes of complete…

Combinatorics · Mathematics 2026-04-03 Sean Longbrake , Sam Spiro

Given a `genus' function $g=g(n)$, we let $\mathcal{E}^g$ be the class of all graphs $G$ such that if $G$ has order $n$ (that is, has $n$ vertices) then it is embeddable in a surface of Euler genus at most $g(n)$. Let the random graph $R_n$…

Combinatorics · Mathematics 2021-08-18 Colin McDiarmid , Sophia Saller

A recent result of Chepoi, Estellon and Vaxes [DCG '07] states that any planar graph of diameter at most 2R can be covered by a constant number of balls of size R; put another way, there are a constant-sized subset of vertices within which…

Computational Geometry · Computer Science 2014-04-01 Glencora Borradaile , Erin Wolf Chambers

We regard a smooth, $d=2$-dimensional manifold $\mathcal{M}$ and its normal tiling $M$, the cells of which may have non-smooth or smooth vertices (at the latter, two edges meet at 180 degrees.) We denote the average number (per cell) of…

Differential Geometry · Mathematics 2022-01-06 Gábor Domokos , Ákos G. Horváth , Krisztina Regős

A connected topological drawing of a graph divides the plane into a number of cells. The type of a cell $c$ is the cyclic sequence of crossings and vertices along the boundary walk of $c$. For example, all triangular cells with three…

Combinatorics · Mathematics 2026-03-10 Benedikt Hahn , Torsten Ueckerdt , Birgit Vogtenhuber

An old problem of Erd\H{o}s, Fajtlowicz and Staton asks for the order of a largest induced regular subgraph that can be found in every graph on n vertices. Motivated by this problem, we consider the order of such a subgraph in a typical…

Combinatorics · Mathematics 2008-08-15 Michael Krivelevich , Benny Sudakov , Nicholas Wormald

The Cycle double cover (CDC) conjecture states that for every bridgeless graph $G$, there exists a family $\mathcal{F}$ of cycles such that each edge of the graph is contained in exactly two members of $\mathcal{F}$. Given an embedding of a…

Combinatorics · Mathematics 2025-11-11 Babak Ghanbari , Robert Šámal
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