On Time, and Space, and Width, and Depth
Talkat 50 Years of Satisfiability: The Centrality of SAT in the Theory of Computing · 2021-02-11..05-13
summary
Asserts that many resolution measures collapse into a small structural picture: up to log and quasi‑polynomial factors, log of resolution size is bounded by width, and Ben‑Sasson–Wigderson style separations show width ≠ tree‑like size; pebbling contradictions give concrete DAG formulas whose pebbling complexity lower bounds depth and force large refutations; introduces positive depth and shows examples with constant clause space but tree‑like size ≥ n^2. Tools: pebbling (including black‑white), algebraic polynomial calculus/monomial space, DNF‑resolution. Main open problems: separate clause/variable/monomial spaces from width and decide whether amortized (star) measures differ.
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