⊦ st[rkvs + rkvs0] = (st[rkvs][rkvs0])
⊦ st[(rk × val) '] = st[rk, val]
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ (rkvs + rkvs0) + rkvs1 = rkvs + rkvs0 + rkvs1])]]