Research proof index

Let t₂ be a thread pool such that t₁ under state σ₁ makes a (single) step to threadpool t₂ and state σ₂. Let thread pools t₁ and t₃ be such that each thread in t₁ makes (zero or more) pure steps to the corresponding thread in t₃. In this situation, either the step from t₁ to t₂ corresponds to one of the pure steps between t₁ and `t...

adequate gives a WP with a pure postcondition from an adequate fact.

Induction principle for finite sets.

Proper subsets have strictly smaller size.

Disjointness of insert m₁ i x and m₂ decomposes into freshness of i in m₂ and the disjointness of m₁ and m₂.

Union is disjoint iff both parts are disjoint.