| # kx = # ax ⊦ key ∈ ri[kx, ax] ↔ key ∈ ri ∨ key ∈ kx |
#(key0 + kx0) = # ax, ∀ ax, key, ri. # kx0 = # ax → (key ∈ ri[kx0, ax] ↔ key ∈ ri ∨ key ∈ kx0) ⊦ key ∈ ri[key0 + kx0, ax] ↔ key ∈ ri ∨ 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)