Adequacy of SimpleSub’s co-occurrence-based simplification analyses

Determine whether the co-occurrence-based simplification analyses used in SimpleSub capture the full extent of desirable simplifications on type variables within algebraic subtyping-based type inference for binaries.

Background

In discussing type simplification, the paper contrasts two strategies: the automata-based simplification inspired by MLSub and the co-occurrence-based simplification presented in SimpleSub. BinSub adopts the automata-based approach to obtain compact types and leverage standard automata minimization techniques.

The authors explicitly note uncertainty about whether SimpleSub’s co-occurrence analyses suffice to capture all desirable simplifications on type variables. Clarifying this would help determine when the lighter-weight co-occurrence method is adequate versus when automata-based simplification is necessary to achieve comparable compactness and precision.