r ∈ H, (r => o0 * P)(H[r, o1]) ⊦ o0 = o1
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ P0 * P1 = P1 * P0], [CSIMPSEQ : ⊦ (P0 * P1) * P2 = P0 * P1 * P2])]]