true, ∀ H, r, H0. # H < # H1 → (true → (r ∈ H0 \ H ↔ r ∈ H0 ∧ ¬ r ∈ H)) ⊦ r ∈ H0 \ H1 ↔ r ∈ H0 ∧ ¬ r ∈ H1
[[CONCRETESIMPRULES : ([CSIMPLESSPRED : <])], [EXTRATERMS : (# H1)]]