LAX launches: natural math language meets Lean, already formalizes NL=coNL

fortnow · x · 2026-09-17

LAX launched today as a way to connect natural mathematical language with Lean. It provides machinery for defining complexity classes and has formalized results such as the Immerman–Szelepcsényi theorem (NL=coNL), proven by inductive counting on finite configuration graphs, constructing a nondeterministic Turing machine that generates paths and census witnesses sequentially, halts on every branch, and uses logarithmic space. The archived entry was formalized by Édouard Bonnet using Codex 5.6 and 6, built on Lean v4.33.0 and mathlib, with a concept map, proof network, and community review via ORCID.

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