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Stochastic Kronecker graphs are a model for complex networks where each edge is present independently according the Kronecker (tensor) product of a fixed matrix k-by-k matrix P with entries in [0,1]. We develop a novel correspondence…

Combinatorics · Mathematics 2015-04-02 Mary Radcliffe , Stephen J. Young

Markov networks are probabilistic graphical models that employ undirected graphs to depict conditional independence relationships among variables. Our focus lies in constraint-based structure learning, which entails learning the undirected…

Machine Learning · Computer Science 2024-03-14 Tuukka Korhonen , Fedor V. Fomin , Pekka Parviainen

The famous Gallai's Conjecture states that any connected graph with n vertices has a path decomposition containing at most (n+1)/2 paths. In this note, we explore graphs generated from removing edges from complete graphs. We first provide…

Combinatorics · Mathematics 2022-11-01 Hua Wang , Andrew Zhang

The graph reconstruction conjecture states that all graphs on at least three vertices are determined up to isomorphism by their deck. In this paper, a general framework for this problem is proposed to simply explain the reconstruction of…

Combinatorics · Mathematics 2018-10-26 Ameneh Farhadian

The game of Cops and Robbers is a well known pursuit-evasion game played on graphs. It has been proved \cite{bounded_degree} that cubic graphs can have arbitrarily large cop number $c(G)$, but the known constructions show only that the set…

The purpose of this paper is to develop a "calculus" on graphs that allows graph theory to have new connections to analysis. For example, our framework gives rise to many new partial differential equations on graphs, most notably a new…

Discrete Mathematics · Computer Science 2007-05-23 Joel Friedman , Jean-Pierre Tillich

We prove the following results for projective klt pairs of dimension $3$ over an algebraically closed field of char $p>5$: the cone theorem, the base point free theorem, the contraction theorem, finiteness of minimal models, termination…

Algebraic Geometry · Mathematics 2014-10-17 Caucher Birkar , Joe Waldron

Inspired by Viennot's observation that matching polynomials are numerators of branched continued fractions we present a proof of the Heilmann-Lieb Theorem.

Combinatorics · Mathematics 2020-04-27 Thomás Jung Spier

For two integers $k$ and $\ell$, an $(\ell \text{ mod }k)$-cycle means a cycle of length $m$ such that $m\equiv \ell\pmod{k}$. In 1977, Bollob\'{a}s proved a conjecture of Burr and Erd\H{o}s by showing that if $\ell$ is even or $k$ is odd,…

Combinatorics · Mathematics 2025-07-18 Hojin Chu , Boram Park , Homoon Ryu

We show that there exists only one duality pair for ordered graphs. We will also define a corresponding definition of $\chi^<$-boundedness for ordered graphs and show that all ordered graphs are $\chi^<$-bounded and prove an analogy of…

Combinatorics · Mathematics 2025-12-18 Michal Čertík , Jaroslav Nešetřil

We present an explicit family of hypergraphs with arbitrarily large uniformity and chromatic number that admit realizations in both geometric and number-theoretic settings. As an application, we give a new proof of a theorem of Chen, Pach,…

Combinatorics · Mathematics 2026-02-23 Gábor Damásdi

We prove a conjecture of Geelen that every proper vertex-minor-closed class of graphs is $\chi$-bounded.

Combinatorics · Mathematics 2021-10-01 James Davies

Addressing a question posed by Chen and Ma from an asymptotic point of view, we present a short proof for the edge density needed to guarantee that two vertices of the same degree are connected by a path of a fixed length. In particular, we…

Combinatorics · Mathematics 2026-05-12 Yamaan Attwa , Matías Azócar Carvajal , Simona Boyadzhiyska , Théo Pierron , Anusch Taraz

We prove that if an $n$-vertex graph $G$ can be drawn in the plane such that each pair of crossing edges is independent and there is a crossing-free edge that connects their endpoints, then $G$ has $O(n)$ edges. Graphs that admit such…

Combinatorics · Mathematics 2016-08-31 Eyal Ackerman , Balázs Keszegh , Mate Vizer

Deciding whether a planar graph (even of maximum degree $4$) is $3$-colorable is NP-complete. Determining subclasses of planar graphs being $3$-colorable has a long history, but since Gr\"{o}tzsch's result that triangle-free planar graphs…

Combinatorics · Mathematics 2020-05-15 François Dross , Borut Lužar , Mária Maceková , Roman Soták

Given $k\ge 1$, a $k$-proper partition of a graph $G$ is a partition ${\mathcal P}$ of $V(G)$ such that each part $P$ of ${\mathcal P}$ induces a $k$-connected subgraph of $G$. We prove that if $G$ is a graph of order $n$ such that…

We prove that deciding whether the edge set of a graph can be partitionned into two spanning trees with orientation constraints is NP-complete. If P $\neq$ NP then this disproves a conjecture of Recski.

Combinatorics · Mathematics 2013-04-15 Olivier Durand de Gevigney

We find the number of partitions of $n$ whose BG-rank is $j$, in terms of $pp(n)$, the number of pairs of partitions whose total number of cells is $n$, giving both bijective and generating function proofs. Next we find congruences mod 5…

Combinatorics · Mathematics 2007-05-23 William Y. C. Chen , Kathy Q. Ji , Herbert S. Wilf

We prove a Riemann-Roch theorem for real divisors on edge-weighted graphs over the reals, extending the result of Baker and Norine for integral divisors on graphs with multiple edges.

Algebraic Geometry · Mathematics 2017-11-13 Rodney James , Rick Miranda

It is conjectured that the Laplacian spectrum of a graph is majorized by its conjugate degree sequence. In this paper, we prove that this majorization holds for a class of graphs including trees. We also show that a generalization of this…

Combinatorics · Mathematics 2007-05-23 Tamon Stephen