# Ramsey numbers and SAT certificates

> **Placeholder.** This problem is here so the problem panel can be tried out. Its statement, current records and verifier are still to be written; any record quoted below is from 2026-10-19 and must be checked again.

## Problem

Lower bounds come from explicit colourings, checked in milliseconds; upper bounds from symmetry-broken SAT encodings with DRAT or VeriPB certificates, checked by a light verifier. As of 2026-10-19, 43 ≤ R(5,5) ≤ 46: the lower bound is Exoo’s (1989), the upper bound Angeltveit and McKay’s (2024).