| ⊦ keys(fs[adr, nd], ax) = keys(fs, ax), adr ∈ ax |
∀ fs, adr, nd. keys(fs[adr, nd], ax0) = keys(fs, ax0) ∨ adr ∈ ax0 ⊦ keys(fs[adr, nd], adr0 + ax0) = keys(fs, adr0 + ax0), adr ∈ adr0 + ax0
Used simplifier rules: keys-base: ⊦ keys(fs, []) = [];%address-list freely generated by [], +;;