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Enhancing universe polymorphism for Rocq: Algebraic universes, consistency checking(…)

Talkat RocqPL 2026 · on Saturday, 2026-01-17· [compilers-and-language-design]
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Mechanical refinement of Bezem–Coquand’s decision procedure is implemented and machine-verified inside a Rocq branch, producing a concrete universe model and an API that accepts algebraic universes (0, +1, max) and performs polynomial-time satisfiability and validity checks with incremental loop detection. The implementation removes the old refresh-universes dance, enables direct substitution/instantiation during elaboration, and exposes a variance-based minimization that drops irrelevant universe constraints. Preliminary experience reuses a state-of-the-art solver that previously yielded ~30% faster checks and shows substantially fewer fresh levels and constraints in polymorphic cumulativity.

AI-written summary · about

  1. 0:00Universe polymorphism in Rocq
  2. 1:58Universe unification challenges
  3. 3:22Efficient type inference constraints
  4. 6:10Consistency checking algorithm
  5. 9:21New model implementation
  6. 12:12Universe variance and minimization
  7. 14:01Working with polymorphism modes
  8. 14:22Q&A on unification
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