| dups((a0 + x0) -1l a), ∀ a. dups(x0 -1l a) → dups(x0) ⊦ dups(a0 + x0) |
dups((a0 ' + x0) -1l a), ∀ a1. ¬ dups(x0 -1l a1) ⊦ dups(x0), a0 ∈ x0
Used simplifier rules: a: ⊦ (x + y) + z = x + y + z; from specification list% ⊦ dups(a ' + x) ↔ dups(x) ∨ a ∈ x; (ws)% ⊦ a + x = a ' + x; (s)