Finite reduction of the universal cluster closure

Establish a general finite reduction that replaces the potentially infinite family of 3-uniform hypergraph clusters in the linear-programming constraints for π(r,k) without changing the value of the linear program.

Background

The upper-bound method formulates a linear program whose constraints are indexed by the family of cluster isomorphism types generated by specified merging rules. Although some constraints can be reduced using repeated claim sets, the cluster family appearing in the constraints may still be infinite.

A general finite replacement would make the method computationally tractable without altering the resulting upper bound. The paper explicitly notes that no general reduction is known, so this remains an unresolved methodological problem.

References

The number of constraints in~lp:F may be infinite and the authors do not know any general reduction that replaces ${r}{k}$ with a finite family without affecting the value of the LP.

— The quadratic Brown--Erdős--Sós problem for 3-uniform hypergraphs with 8 and 9 edges  (2610.03323 - Bodnár et al., 2 Oct 2026) in Remark 2.14, Section 2, subsection “The linear programming problem”