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A graph is called (generically) rigid in $\mathbb{R}^d$ if, for any choice of sufficiently generic edge lengths, it can be embedded in $\mathbb{R}^d$ in a finite number of distinct ways, modulo rigid transformations. Here we deal with the…

计算几何 · 计算机科学 2017-01-26 Ioannis Z. Emiris , Ioannis Psarros

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…

组合数学 · 数学 2011-01-14 Bojan Mohar

We show that for all $n \equiv 0 \pmod{6}$, $n \geq 18$, there is an orientable triangular embedding of the octahedral graph on $n$ vertices that can be augmented with handles to produce a genus embedding of the complete graph of the same…

组合数学 · 数学 2024-12-24 Timothy Sun

Rigidity theory studies the properties of graphs that can have rigid embeddings in a euclidean space $\mathbb{R}^d$ or on a sphere and which in addition satisfy certain edge length constraints. One of the major open problems in this field…

代数几何 · 数学 2021-02-05 Evangelos Bartzos , Ioannis Z. Emiris , Jan Legerský , Elias Tsigaridas

In this paper, we analyze embeddings of grid graphs on orientable surfaces. We determine the genus of a large class of k-dimensional grid graphs and effective two-sided bounds for the genus of any 3-dimensional grid graph, both in terms of…

组合数学 · 数学 2022-04-20 Christian Millichap , Fabian Salinas

We present the first algorithm to morph graphs on the torus. Given two isotopic essentially 3-connected embeddings of the same graph on the Euclidean flat torus, where the edges in both drawings are geodesics, our algorithm computes a…

计算几何 · 计算机科学 2020-07-17 Erin Wolf Chambers , Jeff Erickson , Patrick Lin , Salman Parsa

A platypus graph is a non-hamiltonian graph for which every vertex-deleted subgraph is traceable. They are closely related to families of graphs satisfying interesting conditions regarding longest paths and longest cycles, for instance…

组合数学 · 数学 2017-12-15 Jan Goedgebeur , Addie Neyt , Carol T. Zamfirescu

We consider spherical quadrangulations -- spherical embeddings of multigraphs, possibly with loops, so that every face has boundary walk of length 4 -- in which all vertices have degree 3 or 4. Interpreting each degree 4 vertex as a…

组合数学 · 数学 2022-01-13 Lowell Abrams , Yosef Berman , Vance Faber , Michael Murphy

The number of embeddings of minimally rigid graphs in $\mathbb{R}^D$ is (by definition) finite, modulo rigid transformations, for every generic choice of edge lengths. Even though various approaches have been proposed to compute it, the gap…

代数几何 · 数学 2020-01-24 Evangelos Bartzos , Ioannis Emiris , Jan Legerský , Elias Tsigaridas

Work of Glover and Huneke shows that a cubic graph embeds into the real projective plane if and only if it does not contain one of six topological minors called cubic projective plane obstructions. Here we classify up to equivalence the…

组合数学 · 数学 2024-10-01 Marie Kramer

The dual of a polyhedron is a polyhedron -- or in graph theoretical terms: the dual of a 3-connected plane graph is a 3-connected plane graph. Astonishingly, except for sufficiently large facewidth, not much is known about the connectivity…

组合数学 · 数学 2021-10-20 Drago Bokal , Gunnar Brinkmannb , Carol T. Zamfirescu

A graph is called (generically) rigid in R^d if, for any choice of sufficiently generic edge lengths, it can be embedded in R^d in a finite number of distinct ways, modulo rigid transformations. Here, we deal with the problem of determining…

计算几何 · 计算机科学 2014-10-24 Stylianos C. Despotakis , Ioannis Z. Emiris

A longstanding open question of Archdeacon and Craft asks whether every complete graph has a minimum genus embedding with at most one nontriangular face. We exhibit such an embedding for each complete graph except $K_8$, the complete graph…

组合数学 · 数学 2018-08-31 Timothy Sun

We consider the thickness $\theta (G))$ and outerthickness $\theta _o(G)$ of a graph G in terms of its orientable and nonorientable genus. Dean and Hutchinson provided upper bounds for thickness of graphs in terms of their orientable genus.…

组合数学 · 数学 2015-12-17 Baogang Xu , Xiaoya Zha

We compute the quadratic embedding constant for complete bipartite graphs with disjoint edges removed. Moreover, we study the quadratic embedding property for theta graphs, i.e., graphs consisting of three paths with common initial points…

组合数学 · 数学 2024-10-02 Wojciech Młotkowski , Marek Skrzypczyk , Michał Wojtylak

In this paper we consider the problem of embedding almost-spanning, bounded degree graphs in a random graph. In particular, let $\Delta\geq 5$, $\varepsilon > 0$ and let $H$ be a graph on $(1-\varepsilon)n$ vertices and with maximum degree…

组合数学 · 数学 2017-08-04 Asaf Ferber , Kyle Luh , Oanh Nguyen

We show that no cubic graphs of order 26 have crossing number larger than 9, which proves a conjecture of Ed Pegg Jr and Geoffrey Exoo that the smallest cubic graphs with crossing number 11 have 28 vertices. This result is achieved by first…

组合数学 · 数学 2019-05-17 Kieran Clancy , Michael Haythorpe , Alex Newcombe , Ed Pegg

A conjecture of Berge suggests that every bridgeless cubic graph can have its edges covered with at most five perfect matchings. Since three perfect matchings suffice only when the graph in question is $3$-edge-colourable, the rest of cubic…

组合数学 · 数学 2020-08-05 Edita Máčajová , Martin Škoviera

By definition, a rigid graph in $\mathbb{R}^d$ (or on a sphere) has a finite number of embeddings up to rigid motions for a given set of edge length constraints. These embeddings are related to the real solutions of an algebraic system.…

组合数学 · 数学 2021-10-26 Evangelos Bartzos , Ioannis Z. Emiris , Raimundas Vidunas

Let $\mathbb{S}_g$ be the orientable surface of genus $g$. We show that the number of vertex-labelled cubic multigraphs embeddable on $\mathbb{S}_g$ with $2n$ vertices is asymptotically $c_g n^{5(g-1)/2-1}\gamma^{2n}(2n)!$, where $\gamma$…

组合数学 · 数学 2016-04-12 Wenjie Fang , Mihyun Kang , Michael Moßhammer , Philipp Sprüssel
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