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Deciding whether a graph can be embedded in a grid using only unit-length edges is NP-complete, even when restricted to binary trees. However, it is not difficult to devise a number of graph classes for which the problem is polynomial, even…

Data Structures and Algorithms · Computer Science 2012-04-13 Vinícius G. P. de Sá , Guilherme D. da Fonseca , Raphael Machado , Celina M. H. de Figueiredo

In a sequence of four papers, we prove the following results (via a unified approach) for all sufficiently large $n$: (i) [1-factorization conjecture] Suppose that $n$ is even and $D\geq 2\lceil n/4\rceil -1$. Then every $D$-regular graph…

Combinatorics · Mathematics 2014-10-24 Béla Csaba , Daniela Kühn , Allan Lo , Deryk Osthus , Andrew Treglown

Halin [1965] proved that if a graph has $n$ many pairwise disjoint rays for each $n$ then it has infinitely many pairwise disjoint rays. We analyze the complexity of this and other similar results in terms of computable and proof theoretic…

Logic · Mathematics 2023-08-29 James S. Barnes , Jun Le Goh , Richard A. Shore

Let G be a plane graph and T an even subset of its vertices. It has been conjectured that if all T-cuts of G have the same parity and the size of every T-cut is at least k, then G contains k edge-disjoint T-joins. The case k=3 is equivalent…

Combinatorics · Mathematics 2014-04-25 Zdenek Dvorak , Ken-ichi Kawarabayashi , Daniel Kral

In this paper we have shown without assuming the four color theorem of planar graphs that every (bridgeless) cubic planar graph has a three-edge-coloring. This is an old-conjecture due to Tait in the squeal of efforts in settling the…

Combinatorics · Mathematics 2007-05-23 I. Cahit

Clustering is an important topic in algorithms, and has a number of applications in machine learning, computer vision, statistics, and several other research disciplines. Traditional objectives of graph clustering are to find clusters with…

Machine Learning · Computer Science 2020-11-11 Steinar Laenen , He Sun

Community detection in graphs is a problem that is likely to be relevant whenever network data appears, and consequently the problem has received much attention with many different methods and algorithms applied. However, many of these…

Combinatorics · Mathematics 2025-05-16 Vilhelm Agdur

Clustering is a fundamental task in unsupervised learning. Previous research has focused on learning-augmented $k$-means in Euclidean metrics, limiting its applicability to complex data representations. In this paper, we generalize…

Machine Learning · Computer Science 2025-06-17 Chenglin Fan , Kijun Shin

A simplicial complex of dimension $d-1$ is said to be balanced if its graph is $d$-colorable. Juhnke-Kubitzke and Murai proved an analogue of the generalized lower bound theorem for balanced simplicial polytopes. We establish a…

Combinatorics · Mathematics 2016-08-30 Martina Juhnke-Kubitzke , Satoshi Murai , Isabella Novik , Connor Sawaske

Graph-based subspace clustering methods have exhibited promising performance. However, they still suffer some of these drawbacks: encounter the expensive time overhead, fail in exploring the explicit clusters, and cannot generalize to…

Machine Learning · Computer Science 2021-02-23 Zhao Kang , Zhiping Lin , Xiaofeng Zhu , Wenbo Xu

A well-known conjecture of Gr\"unbaum and Nash-Williams proposes that 4-connected toroidal graphs are hamiltonian. The corresponding results for 4-connected planar and projective-planar graphs were proved by Tutte and by Thomas and Yu,…

Combinatorics · Mathematics 2013-12-06 M. N. Ellingham , Emily A. Marshall

A graph is apex if there is a vertex whose deletion makes the graph planar, and doublecross if it can be drawn in the plane with only two crossings, both incident with the infinite region in the natural sense. In 1966, Tutte conjectured…

Combinatorics · Mathematics 2017-03-28 Katherine Edwards , Daniel P. Sanders , Paul Seymour , Robin Thomas

In 1956, Tutte proved the celebrated theorem that every 4-connected planar graph is hamiltonian. This result implies that every more than $\frac{3}{2}$-tough planar graph on at least three vertices is hamiltonian and so has a 2-factor.…

Combinatorics · Mathematics 2024-04-30 Songling Shan

We introduce and study the $\textit{OrthoSEFE}-k$ problem: Given $k$ planar graphs each with maximum degree 4 and the same vertex set, do they admit an OrthoSEFE, that is, is there an assignment of the vertices to grid points and of the…

This paper is an exploration of simple four-regular graphs in the plane (i.e. loopless and with no more than one edge between any two nodes). Such graphs are fundamental to the theory of knots and links in three dimensional space, and their…

Combinatorics · Mathematics 2021-08-19 Shalom Eliahou , Frank Harary , Louis H. Kauffman

We prove that for any parameter r an r-locally 2-connected graph G embeds r-locally planarly in a surface if and only if a certain matroid associated to the graph G is co-graphic. This extends Whitney's abstract planar duality theorem from…

Combinatorics · Mathematics 2020-11-20 Johannes Carmesin

Algebraic curves have a discrete analogue in finite graphs. Pursuing this analogy we prove a Torelli theorem for graphs. Namely, we show that two graphs have the same Albanese torus if and only if the graphs obtained from them by…

Combinatorics · Mathematics 2019-12-19 Lucia Caporaso , Filippo Viviani

Graph pattern matching is a routine process for a wide variety of applications such as social network analysis. It is typically defined in terms of subgraph isomorphism which is NP-Complete. To lower its complexity, many extensions of graph…

Databases · Computer Science 2018-04-13 Houari Mahfoud

Graph clustering is a central topic in unsupervised learning with a multitude of practical applications. In recent years, multi-view graph clustering has gained a lot of attention for its applicability to real-world instances where one has…

Machine Learning · Computer Science 2024-06-10 Vincent Cohen-Addad , Tommaso d'Orsi , Silvio Lattanzi , Rajai Nasser

In the projective plane PG(2,q) over a finite field of order q, a Tallini curve is a plane irreducible (algebraic) curve of (minimum) degree q+2 containing all points of PG(2,q). Such curves were investigated by G. Tallini in 1961, and by…

Algebraic Geometry · Mathematics 2018-07-12 Gregory Duran Cunha