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Mark Jungerman's 1975 Ph.D. thesis presents several infinite families of index 2 current graphs that generate triangular embeddings of complete or near-complete graphs. However, there is one family mentioned, the complete graphs on $36s$…

组合数学 · 数学 2025-09-09 Avinh Huynh , Timothy Sun

We construct several families of minimum genus embeddings of dense graphs using index 2 current graphs. In particular, we complete the genus formula for the octahedral graphs, solving a longstanding conjecture of Jungerman and Ringel, and…

组合数学 · 数学 2023-06-26 Timothy Sun

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

We show that the complete graphs on $24s+21$ vertices have decompositions into two edge-disjoint subgraphs, each of which triangulates an orientable surface. The special case where the two surfaces are homeomorphic solves a generalized…

组合数学 · 数学 2023-01-03 Juvenal F. Barajas , Timothy Sun

The genus graphs have been studied by many authors, but just a few results concerning in special cases: Planar, Toroidal, Complete, Bipartite and Cartesian Product of Bipartite. We present here a derive general lower bound for the genus of…

一般拓扑 · 数学 2016-01-05 J. E. Strapasson , S. I. R. Costa , M. M. S. Alves

The problems of the genus of the complete graphs and minimum triangulations for each surface were both solved using the theory of current graphs, and each of them divided into twelve different cases, depending on the residue modulo 12 of…

组合数学 · 数学 2019-02-04 Timothy Sun

The current state of knowledge of genus g orientable crossing numbers of complete graphs through K11 is reviewed. It is shown that cr3(K10)=3, cr3(K11)<=14, and cr4(K11)=4. It is established with the aid of an algorithm that there are…

组合数学 · 数学 2019-02-08 Yoonah Lee

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

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…

组合数学 · 数学 2010-01-19 Jin Ho Kwak , Young Soo Kwon

The regular embeddings of complete bipartite graphs $K_{n,n}$ in orientable surfaces are classified and enumerated, and their automorphism groups and combinatorial properties are determined. The method depends on earlier classifications in…

组合数学 · 数学 2014-02-26 Gareth A. Jones

The complete sets of irreducible triangulations are known for the orientable surfaces with genus of 0, 1, or 2 and for the nonorientable surfaces with genus of 1, 2, 3, or 4. By examining these sets we determine some of the properties of…

组合数学 · 数学 2007-05-23 Thom Sulanke

A {\em $1-$vertex triangulation} of an oriented compact surface $S$ of genus $g$ is an embedded graph $T\subset S$ with a unique vertex such that all connected components of $S\setminus T$ are triangles (adjacent to exactly 3 edges of $T$).…

组合数学 · 数学 2007-05-23 Roland Bacher , Alina Vdovina

An embedding of a graph on an orientable surface is orientably-regular (or rotary, in an equivalent terminology) if the group of orientation-preserving automorphisms of the embedding is transitive (and hence regular) on incident vertex-edge…

组合数学 · 数学 2023-11-17 Stefan Gyurki , Sona Pavlikova , Jozef Siran

We describe an infinite family of edge-decompositions of complete graphs into two graphs, each of which triangulate the same orientable surface. Previously, such decompositions had only been known for only a few complete graphs. These…

组合数学 · 数学 2021-11-24 Timothy Sun

With the $[0,1,2]$-family of cyclic triangulations we introduce a rich class of vertex-transitive triangulations of surfaces. In particular, there are infinite series of cyclic $q$-equivelar triangulations of orientable and non-orientable…

组合数学 · 数学 2010-01-19 Frank H. Lutz

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

A class of graphs that lies strictly between the classes of graphs of genus (at most) $k-1$ and $k$ is studied. For a fixed orientable surface $S_k$ of genus $k$, let $A_{xy}^k$ be the minor-closed class of graphs with terminals $x$ and $y$…

组合数学 · 数学 2011-12-06 Bojan Mohar , Petr Škoda

We give an algorithm to calculate the minimal and maximal genus of the orientable closed surface where a graph $G$ can be embedded. For this, we construct some special branched coverings of the 2-sphere. We apply this algorithm to calculate…

几何拓扑 · 数学 2023-11-27 Lorena Armas-Sanabria , Víctor Núñez

A graph is said to be nearly complete bipartite if it can be obtained by deleting a set of independent edges from a complete bipartite graph. The nonorientable genus of such graphs is known except in a few cases where the sizes of the…

组合数学 · 数学 2023-05-24 Warren Singh , Timothy Sun

A graph is said to be {\em vertex-transitive non-Cayley} if its full automorphism group acts transitively on its vertices and contains no subgroups acting regularly on its vertices. In this paper, a complete classification of cubic…

组合数学 · 数学 2017-05-15 Wei-Juan Zhang , Yan-Quan Feng , Jin-Xin Zhou
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