⊦ H0 = H1 ↔ (∀ r. (r ∈ H0 ↔ r ∈ H1) ∧ (r ∈ H0 → H0[r] = H1[r]))
[[CONCRETESIMPRULES : ()], [EXTRATERMS : ((H ++ r)[r, o] -- r0, ((H -- r0) ++ r)[r, o])]]