Nearly all k-SAT Functions are Unate
summary
Proves that for every fixed k a 1-o(1) fraction of k-SAT Boolean functions on n variables are unate, resolving the Bollobás–Brightwell–Leader conjecture. The proof reduces counting minimal k-SAT DNFs to an extremal problem on partially directed k‑uniform hypergraphs, uses the hypergraph container method to get containers that are semisimple formulae, and completes the Turán-style bound with a short computer‑guided flag algebras (sum‑of‑squares) certificate. Outcome: almost all k‑SAT functions are unate and most have a unique minimal formula; the argument currently requires k fixed.
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chapters (9)
- 0:00Introduction
- 2:38Main theorem on k-SAT functions
- 6:30Problem and historical context
- 14:45Combinatorial enumeration techniques
- 25:05k-SAT functions and forbidden subgraphs
- 31:57Container method and semisimple formulae
- 44:57Extremal problem for hypergraphs
- 51:23Future directions in k-SAT theory
- 1:04:00Question and answer session
