Exact value of f(6)

Determine the exact value of the Poljak–Rödl function f(6), which is known only to be either 4 or 5.

Background

The paper notes that f(5) = 4, whereas the available bounds leave f(6) unresolved between 4 and 5. Determining f(6) is presented as a concrete restricted form of the weak Hedetniemi problem.

References

Can we determine $f(6)$?

— A survey on Hedetniemi's conjecture  (2502.16078 - Zhu, 22 Feb 2025) in Section 5, immediately following Question q1