Erdős Matching Conjecture

Prove the Erdős Matching Conjecture: for every positive integer s, every integer n ≥ (s + 1)k, and every k-uniform hypergraph F on [n] with matching number ν(F) ≤ s, establish that |F| ≤ max{\binom{n}{k} − \binom{n−s}{k}, \binom{(s+1)k−1}{k}}.

Background

The paper places resilient hypergraph questions in the context of the Erdős Matching Conjecture, which seeks the largest possible size of a k-uniform hypergraph with matching number at most s. The conjectured extremal bound is given by the larger of two natural constructions: all k-sets intersecting a fixed s-set, and all k-sets contained in a set of size (s+1)k−1.

The paper notes that the conjecture has been proved in several important regimes, including the case k = 3, but presents it as a major open problem in general. This provides the broader extremal-set-theoretic context for the authors’ study of resilient hypergraphs.

References

One of the most important open problems in extremal set theory is the following. Conjecture 1.1 (Erdős Matching Conjecture [4]). Suppose that s is a positive integer, n ≥ (s + 1)k and F ⊂ ([n]k) satisfies ν(F) ≤ s. Then |F| ≤ max{(n k)−(n − s k),((s + 1)k − 1 k)}. (1.1)

On resilient hypergraphs  (2503.08406 - Frankl et al., 11 Mar 2025) in Section 1, immediately before Conjecture 1.1, p. 1

One of the most important open problems in extremal set theory is the following. Conjecture 1.1 (Erdős Matching Conjecture [4]). Suppose that s is a positive integer, n ≥ (s + 1)k and F ⊂ ([n]k) satisfies ν(F) ≤ s. Then |F| ≤ max{(n k)−(n − s k),((s + 1)k − 1 k)}. (1.1)

On resilient hypergraphs  (2503.08406 - Frankl et al., 11 Mar 2025) in Section 1, immediately before Conjecture 1.1, p. 1

One of the most important open problems in extremal set theory is the following. Conjecture 1.1 (Erdős Matching Conjecture [4]). Suppose that s is a positive integer, n ≥ (s + 1)k and F ⊂ ([n]k) satisfies ν(F) ≤ s. Then |F| ≤ max{(n k)−(n − s k),((s + 1)k − 1 k)}. (1.1)

On resilient hypergraphs  (2503.08406 - Frankl et al., 11 Mar 2025) in Section 1, immediately before Conjecture 1.1, p. 1