| ∀ a. a ∈ x0 → dups(x0 + a '), a ∈ a0 + x0 ⊦ dups((a0 + x0) + a ') |
a ∈ x0, ∀ a. a ∈ x0 → dups(x0 + a ') ⊦ a0 ∈ x0, dups(x0 + a ')
Used simplifier rules: rec: ⊦ dups(a ' + x) ↔ ¬ ¬(a ∈ x ∨ dups(x));%in-17: ⊦ a ∈ b ' ↔ a = b; from specification list%in-append: ⊦ a ∈ x + y ↔ ¬ ¬(a ∈ x ∨ a ∈ y); from specification list%a: ⊦ (x + y) + z = x + y + z; from specification list%in-rec: ⊦ a ∈ b ' + x ↔ ¬ ¬(a = b ∨ a ∈ x); from specification list%c: ⊦ a + x = a ' + x; from specification list