Obtain reasonably small threshold bounds for the Hajnal–Rothschild theorem

Establish reasonably small upper bounds for the threshold \(n_0(k,t,s)\) in the Hajnal–Rothschild theorem, valid for general values of \(k\), \(t\), and \(s\).

Background

The Hajnal–Rothschild theorem asserts that sufficiently large n forces every k-uniform family with ν(F,t)s\nu(\mathcal F,t)\le s to have size at most the matching-based construction h(n,k,t,s)h'(n,k,t,s). The threshold n0(k,t,s)n_0(k,t,s) specifies how large n must be for this conclusion to hold.

The paper contrasts the known relatively small bounds in the Erdős Matching Conjecture case t=1t=1 with the much larger bounds arising from the general Hajnal–Rothschild proof. Improving these bounds would make the theorem effective over a substantially broader parameter range.

References

However, in great contrast, we do not know of any reasonably small bounds in the general case of the Hajnal-Rothschild Theorem.

The Hajnal--Rothschild problem  (2502.06699 - Frankl et al., 10 Feb 2025) in Section 1, following Theorem 6, p. 4