| # x = m + 1, a ∈ x ⊦ #(x \ a ') = m, x = [], dups(x) |
∀ m, a. # x0 = m + 1 ∧ a ∈ x0 → #(x0 \ a ') = m ∨ x0 = [] ∨ dups(x0), #(a0 + x0) = m + 1, a ∈ a0 + x0 ⊦ #((a0 + x0) \ a ') = m, a0 + x0 = [], dups(a0 + x0)
Used simplifier rules: list freely generated by [], +;;