| a ∈ y, ∀ a, y. a ∈ y → # rmdup(x0 + a ' + y) = # rmdup(x0 + y) ⊦ #(a0 ' + rmdup(x0 + a ' + y)) = # (a0 ∈ x0 ∨ a0 ∈ y ⊃ rmdup(x0 + y);a0 ' + rmdup(x0 + y)), a0 ∈ x0, a0 ∈ y |
a ∈ y, ∀ a, y. a ∈ y → # rmdup(x0 + a ' + y) = # rmdup(x0 + y) ⊦ 1 + # rmdup(x0 + a ' + y) = 1 + # rmdup(x0 + y), a0 ∈ y, a0 ∈ x0
Used simplifier rules: a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ # a ' = 0 +1; (s)% ⊦ #(x + y) = # x + # y; (s)