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