| # kx = # ax, key ∈ ri ⊦ ri[kx, ax][key] = ri[key], key ∈ kx |
#(key0 + kx0) = # ax, key ∈ ri, ∀ ax, key, ri. # kx0 = # ax ∧ key ∈ ri → ri[kx0, ax][key] = ri[key] ∨ key ∈ kx0 ⊦ ri[key0 + kx0, ax][key] = ri[key], key ∈ key0 + kx0
Used simplifier rules: index-update-key-base: ⊦ ri[[], []] = ri;%key-list freely generated by [], +;;% ⊦ # [] = 0; (s)% ⊦ # ax = 0 ↔ ax = []; (s)% ⊦ ¬ key ∈ []; (s)