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Kolla and Tulsiani [KT07,Kolla11} and Arora, Barak and Steurer [ABS10] introduced the technique of subspace enumeration, which gives approximation algorithms for graph problems such as unique games and small set expansion; the running time…

Data Structures and Algorithms · Computer Science 2012-12-11 Shayan Oveis Gharan , Luca Trevisan

Many important results in extremal graph theory can be roughly summarised as "if a triangle-free graph $G$ has certain properties, then it has a homomorphism to a triangle-free graph $\Gamma$ of bounded size". For example, bounds on…

Combinatorics · Mathematics 2025-04-16 Lior Gishboliner , Eoin Hurley , Yuval Wigderson

We prove a new, efficient version of the hypergraph container theorems that is suited for hypergraphs with large uniformities. The main novelty is a refined approach to constructing containers that employs simple ideas from high-dimensional…

Combinatorics · Mathematics 2020-12-11 József Balogh , Wojciech Samotij

In the $\mathcal{F}$-Minor-Free Deletion problem one is given an undirected graph $G$, an integer $k$, and the task is to determine whether there exists a vertex set $S$ of size at most $k$, so that $G-S$ contains no graph from the finite…

Data Structures and Algorithms · Computer Science 2021-10-06 Huib Donkers , Bart M. P. Jansen , Michał Włodarczyk

Starting from a complete graph on $n$ vertices, repeatedly delete the edges of a uniformly chosen triangle. This stochastic process terminates once it arrives at a triangle-free graph, and the fundamental question is to estimate the final…

Combinatorics · Mathematics 2012-06-11 Tom Bohman , Alan Frieze , Eyal Lubetzky

One of the earliest results in extremal graph theory, Mantel's theorem, states that the maximum number of edges in a triangle-free graph $G$ on $n$ vertices is $\lfloor n^2/4 \rfloor$. We investigate how this extremal bound is affected when…

Combinatorics · Mathematics 2025-07-01 Natalie Behague , Debsoumya Chakraborti , Xizhi Liu

Szemer\'edi's regularity lemma is a fundamental tool in extremal combinatorics. However, the original version is only helpful in studying dense graphs. In the 1990s, Kohayakawa and R\"odl proved an analogue of Szemer\'edi's regularity lemma…

Combinatorics · Mathematics 2015-10-26 David Conlon , Jacob Fox , Yufei Zhao

We consider the problem of estimating undirected triangle-free graphs of high dimensional distributions. Triangle-free graphs form a rich graph family which allows arbitrary loopy structures but 3-cliques. For inferential tractability, we…

Machine Learning · Statistics 2015-04-24 Junwei Lu , Han Liu

The regularity lemma of Szemeredi asserts that one can partition every graph into a bounded number of quasi-random bipartite graphs. In some applications however, one would like to have a strong control on how quasi-random these bipartite…

Combinatorics · Mathematics 2014-02-26 Subrahmanyam Kalyanasundaram , Asaf Shapira

Since many NP-complete graph problems have been shown polynomial-time solvable when restricted to claw-free graphs, we study the problem of determining the distance of a given graph to a claw-free graph, considering vertex elimination as…

Data Structures and Algorithms · Computer Science 2023-10-06 Flavia Bonomo-Braberman , Julliano R. Nascimento , Fabiano S. Oliveira , Uéverton S. Souza , Jayme L. Szwarcfiter

In 1995 Kim famously proved the Ramsey bound R(3,t) \ge c t^2/\log t by constructing an n-vertex graph that is triangle-free and has independence number at most C \sqrt{n \log n}. We extend this celebrated result, which is best possible up…

Combinatorics · Mathematics 2021-04-06 He Guo , Lutz Warnke

We introduce a new conjecture on the computational hardness of detecting random lifts of graphs: we claim that there is no polynomial-time algorithm that can distinguish between a large random $d$-regular graph and a large random lift of a…

Computational Complexity · Computer Science 2024-04-29 Dmitriy Kunisky , Xifan Yu

We give a combinatorial polynomial-time algorithm to find a maximum weight independent set in perfect graphs of bounded degree that do not contain a prism or a hole of length four as an induced subgraph. An even pair in a graph is a pair of…

Combinatorics · Mathematics 2024-01-09 Tara Abrishami , Maria Chudnovsky , Cemil Dibek , Kristina Vušković

Determining the maximum number of edges under degree and matching number constraints have been solved for general graphs by Chv\'{a}tal and Hanson (1976), and by Balachandran and Khare (2009). It follows from the structure of those extremal…

Combinatorics · Mathematics 2022-07-07 Milad Ahanjideh , Tınaz Ekim , Mehmet Akif Yıldız

Quasi-threshold graphs are $\{C_4, P_4\}$-free graphs, i.e., they do not contain any cycle or path of four nodes as an induced subgraph. We study the $\{C_4, P_4\}$-free editing problem, which is the problem of finding a minimum number of…

Data Structures and Algorithms · Computer Science 2020-04-01 Lars Gottesbüren , Michael Hamann , Philipp Schoch , Ben Strasser , Dorothea Wagner , Sven Zühlsdorf

Vertex deletion problems for graphs are studied intensely in classical and parameterized complexity theory. They ask whether we can delete at most k vertices from an input graph such that the resulting graph has a certain property.…

Logic in Computer Science · Computer Science 2024-06-27 Max Bannach , Florian Chudigiewitsch , Till Tantau

For a family $\mathcal{F}$ of graphs, let $ex(n,\mathcal{F})$ denote the maximum number of edges in an $n$-vertex graph which contains none of the members of $\mathcal{F}$ as a subgraph. A longstanding problem in extremal graph theory asks…

Combinatorics · Mathematics 2022-12-06 Jie Ma , Tianchi Yang

For any particular class of graphs, algorithms for computational problems restricted to the class often rely on structural properties that depend on the specific problem at hand. This begs the question if a large set of such results can be…

We revisit a classical paper about (even hole, triangle)-free graphs [Conforti, Cornu\'ejols, Kapoor and Vu\v skovi\'c, Triangle-free graphs that are signable without even holes, Journal of Graph Theory, 34(3), 204--220, 2000]. In fact, the…

Combinatorics · Mathematics 2026-04-03 Beatriz Martins , Nicolas Trotignon

For causal discovery in the presence of latent confounders, constraints beyond conditional independences exist that can enable causal discovery algorithms to distinguish more pairs of graphs. Such constraints are not well-understood yet. In…

Machine Learning · Computer Science 2024-06-14 Thijs van Ommen