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We establish bounds for the covariance of a large class of functions of infinite variance stable random variables, including unbounded functions such as the power function and the logarithm. These bounds involve measures of dependence…

Statistics Theory · Mathematics 2011-11-10 Vladas Pipiras , Murad S. Taqqu , Patrice Abry

We show that the problem of counting the number of Eulerian circuits in an undirected graph is complete for the class #P.

Computational Complexity · Computer Science 2007-05-23 Graham R. Brightwell , Peter Winkler

Consider a random graph process where vertices are chosen from the interval $[0,1]$, and edges are chosen independently at random, but so that, for a given vertex $x$, the probability that there is an edge to a vertex $y$ decreases as the…

Let $s(n)$ be the minimum number of edges in a graph that contains every $n$-vertex tree as a subgraph. Chung and Graham [J. London Math. Soc. 1983] claim to prove that $s(n)\leqslant O(n\log n)$. We point out a mistake in their proof. The…

Combinatorics · Mathematics 2025-08-06 Neel Kaul , David R. Wood

In recent work by Dani and Mainkar, a family of finite simple graphs was used to construct nilmanifolds admitting Anosov diffeomorphisms. Our main object of study is this particular set of graphs, which we call Anosov graphs. Moreover, Dani…

Combinatorics · Mathematics 2020-08-26 Meera Mainkar , Matthew Plante , Ben Salisbury

We extend the concept of the law of a finite graph to graphings, which are, in general, infinite graphs whose vertices are equipped with the structure of a probability space. By doing this, we obtain a vast array of new unimodular measures.…

Combinatorics · Mathematics 2012-03-13 Igor Artemenko

We consider a class of growing random graphs obtained by creating vertices sequentially one by one: at each step, we choose uniformly the neighbours of the newly created vertex; its degree is a random variable with a fixed but arbitrary…

Combinatorics · Mathematics 2013-11-13 Svante Janson , Simone Severini

In the branch of mathematics known as graph theory, graphs are considered as a set of points, called vertices, with connections between these points, called edges. The purpose of this paper is to study mappings between two graphs that have…

Combinatorics · Mathematics 2019-03-19 Jeffrey Beyerl , Cameron Sharpe

We study the problem of finding a copy of a specific induced subgraph on inhomogeneous random graphs with infinite variance power-law degrees. We provide a fast algorithm that finds a copy of any connected graph $H$ on a fixed number of $k$…

Data Structures and Algorithms · Computer Science 2019-08-30 Ellen Cardinaels , Johan S. H. van Leeuwaarden , Clara Stegehuis

The isomorphism problem for planar graphs is known to be efficiently solvable. For planar 3-connected graphs, the isomorphism problem can be solved by efficient parallel algorithms, it is in the class $AC^1$. In this paper we improve the…

Data Structures and Algorithms · Computer Science 2008-02-21 Thomas Thierauf , Fabian Wagner

We study the task of estimating the number of edges in a graph with access to only an independent set oracle. Independent set queries draw motivation from group testing and have applications to the complexity of decision versus counting…

Data Structures and Algorithms · Computer Science 2020-03-13 Paul Beame , Sariel Har-Peled , Sivaramakrishnan Natarajan Ramamoorthy , Cyrus Rashtchian , Makrand Sinha

The "slope-number" of a graph $G$ is the minimum number of distinct edge slopes in a straight-line drawing of $G$ in the plane. We prove that for $\Delta\geq5$ and all large $n$, there is a $\Delta$-regular $n$-vertex graph with…

Combinatorics · Mathematics 2008-09-09 Vida Dujmovic' , Matthew Suderman , David R. Wood

Let $I(G)$ be a topological index of a graph. If $I(G+e)<I(G)$ (or $I(G+e)>I(G)$, respectively) for each edge $e\not\in G$, then $I(G)$ is monotonically decreasing (or increasing, respectively) with the addition of edges. In this article,…

Combinatorics · Mathematics 2017-04-19 Hanlin Chen , Renfang Wu , Hanyuan Deng

Let $\Gamma$ denote the modular group $SL(2,\Bbb Z)$ and $C_n(\Gamma)$ the number of congruence subgroups of $\Gamma$ of index at most $n$. We prove that $\lim\limits_{n\to \infty} \frac{\log C_n(\Gamma)}{(\log n)^2/\log\log n} =…

Group Theory · Mathematics 2007-05-23 D. Goldfeld , A. Lubotzky , L. Pyber

Let $G=(V(G),E(G))$ be a graph with set of vertices $V(G)$ and set of edges $E(G)$. For $k\ge 0$ an integer, a subset $I_k$ of $V(G)$ is called a $k$-nearly independent vertex subset of $G$ if $I_k$ induces a subgraph of size $k$ in $G$.…

Combinatorics · Mathematics 2024-07-15 Zekhaya B. Shozi

This manuscript introduces Diophantine labeling, a new way of labeling of the vertices for finite simple undirected graphs with some divisibility condition on the edges. Maximal graphs admitting Diophantine labeling are investigated and…

Combinatorics · Mathematics 2026-01-01 A. Nasr , A. Elsonbaty , M. A. Seoud , M. Anwar

We consider the problem of determining the inducibility (maximum possible asymptotic density of induced copies) of oriented graphs on four vertices. We provide exact values for more than half of the graphs, and very close lower and upper…

Combinatorics · Mathematics 2022-02-18 Łukasz Bożyk , Andrzej Grzesik , Bartłomiej Kielak

We enumerate graph homomorphisms to quasi-complete graphs, i.e., graphs obtained from complete graphs by removing one edge. The source graphs are complete graphs, quasi-complete graphs, cycles, paths, wheels and broken wheels. These…

Combinatorics · Mathematics 2016-01-26 Pedro Lopes

We study the number of non-isomorphic functional graphs of affine-linear transformations from (\F_q)^n to itself, and we prove upper and lower bounds on this quantity for n large. As a corollary to our result, we prove bounds on the number…

Number Theory · Mathematics 2013-02-20 Eric Bach , Andrew Bridy

We study the asymptotic shape of random unlabelled graphs subject to certain subcriticality conditions. The graphs are sampled with probability proportional to a product of Boltzmann weights assigned to their $2$-connected components. As…

Combinatorics · Mathematics 2017-12-06 Benedikt Stufler