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A graph is called Rank-Ramsey if (i) Its clique number is small, and (ii) The adjacency matrix of its complement has small rank. We initiate a systematic study of such graphs. Our main motivation is that their constructions, as well as…

Combinatorics · Mathematics 2024-10-21 Gal Beniamini , Nati Linial , Adi Shraibman

We show that a restricted version of a conjecture of M. Talagrand on the relation between "expectation thresholds" and "fractional expectation thresholds" follows easily from a strong version of a second conjecture of Talagrand, on…

Combinatorics · Mathematics 2024-12-03 Quentin Dubroff , Jeff Kahn , Jinyoung Park

Structured prediction tasks in machine learning involve the simultaneous prediction of multiple labels. This is typically done by maximizing a score function on the space of labels, which decomposes as a sum of pairwise elements, each…

Machine Learning · Computer Science 2014-09-23 Amir Globerson , Tim Roughgarden , David Sontag , Cafer Yildirim

We prove that a formula predicted on the basis of non-rigorous physics arguments [Zdeborova and Krzakala: Phys. Rev. E (2007)] provides a lower bound on the chromatic number of sparse random graphs. The proof is based on the interpolation…

Combinatorics · Mathematics 2021-10-20 Peter Ayre , Amin Coja-Oghlan , Catherine Greenhill

We study the computational power of polynomial threshold functions, that is, threshold functions of real polynomials over the boolean cube. We provide two new results bounding the computational power of this model. Our first result shows…

Computational Complexity · Computer Science 2009-11-29 Ido Ben-Eliezer , Shachar Lovett , Ariel Yadin

In 1992, Kalai and Kleitman proved the first subexponential upper bound for the diameters of convex polyhedra. Eisenbrand et al. proved this bound holds for connected layer families, a novel approach to analyzing polytope diameters. Very…

Combinatorics · Mathematics 2014-12-19 J. Mackenzie Gallagher , Edward D. Kim

We revisit results obtained in [F. Harary, U. Peled, Hamiltonian threshold graphs, Discrete Appl.~Math., 16 (1987), 11--15], where several necessary and necessary and sufficient conditions for a connected threshold graph to be Hamiltonian…

Combinatorics · Mathematics 2021-02-17 Milica Andelic , Tamara Koledin , Zoran Stanic

The problem of constructing explicit functions which cannot be approximated by low degree polynomials has been extensively studied in computational complexity, motivated by applications in circuit lower bounds, pseudo-randomness,…

Computational Complexity · Computer Science 2014-12-16 Abhishek Bhowmick , Shachar Lovett

In this paper we extend a classical theorem of Corr\'adi and Hajnal into the setting of sparse random graphs. We show that if $p(n) \gg (\log n / n)^{1/2}$, then asymptotically almost surely every subgraph of $G(n,p)$ with minimum degree at…

Combinatorics · Mathematics 2011-11-02 József Balogh , Choongbum Lee , Wojciech Samotij

In 2014, Flynn and the second author bounded the average number of components of the functional graphs of polynomials of fixed degree over a finite field. When the fixed degree was large (relative to the size of the finite field), their…

Dynamical Systems · Mathematics 2018-01-11 Elisa Bellah , Derek Garton , Erin Tannenbaum , Noah Walton

By considering graphs as discrete analogues of Riemann surfaces, Baker and Norine (Adv. Math. 2007) developed a concept of linear systems of divisors for graphs. Building on this idea, a concept of gonality for graphs has been defined and…

Combinatorics · Mathematics 2016-07-12 Kevin Hendrey

Neglecting many motivating details for the Park-Pham theorem (previously known as the Kahn-Kalai conjecture), the result starts with a finite set $X$, a non-trivial upper set $\mathcal{F} \subseteq 2^X$, and a particular parameterized…

Combinatorics · Mathematics 2024-08-16 Bryce Alan Christopherson , Darian Colgrove

In a seminal paper, Alon and Tarsi have introduced an algebraic technique for proving upper bounds on the choice number of graphs (and thus, in particular, upper bounds on their chromatic number). The upper bound on the choice number of $G$…

Combinatorics · Mathematics 2009-11-12 Dan Hefetz

We present two new contributions to the study of the independence polynomial $Z_G(z)$ of a finite simple graph $G = (V,E)$. First, we provide an improved lower bound for the zero-free region of $Z_G(z)$ for the important class of claw-free…

Combinatorics · Mathematics 2025-08-15 Paula M. S. Fialho , Aldo Procacci

Ajtai, Koml\'os, and Szemer\'edi proved that for sufficiently large $t$ every triangle-free graph with $n$ vertices and average degree $t$ has an independent set of size at least $\frac{n}{100t}\log{t}$. We extend this by proving that the…

Combinatorics · Mathematics 2011-11-17 Jeff Cooper , Dhruv Mubayi

Recently there has been much interest in studying random graph analogues of well known classical results in extremal graph theory. Here we follow this trend and investigate the structure of triangle-free subgraphs of $G(n,p)$ with high…

Combinatorics · Mathematics 2015-07-21 Peter Allen , Julia Böttcher , Yoshiharu Kohayakawa , Barnaby Roberts

This paper discusses the complete structure of the (bull, diamond)-free graphs. As an application of that, we give the characterization of the partitionable (bull, diamond)-free graphs. Moreover, we show that such a partition for a…

Combinatorics · Mathematics 2024-08-20 Suchismita Mishra

In this note, we consider the width of a supercritical random graph according to some commonly studied width measures. We give short, direct proofs of results of Lee, Lee and Oum, and of Perarnau and Serra, on the rank- and tree-width of…

Combinatorics · Mathematics 2024-01-29 Tuan Anh Do , Joshua Erde , Mihyun Kang

Motivated by Chudnovsky's structure theorem of bull-free graphs, Abu-Khzam, Feghali, and M\"uller have recently proved that deciding if a graph has a vertex partition into disjoint cliques and a triangle-free graph is NP-complete for five…

Discrete Mathematics · Computer Science 2015-12-08 Marin Bougeret , Pascal Ochem

We improve upper bounds of F. R. K. Chung and of M. Lu, D. Wan, L.-P. Wang, X.-D. Zhang on the diameter of some Cayley graphs constructed from polynomials over finite fields.

Number Theory · Mathematics 2014-02-17 Igor E. Shparlinski