| dups(filter(a ' + x0, y)), ∀ y0. ¬ dups(filter(x0, y0)) ⊦ a ∈ y, a ∈ x0, dups(x0) |
dups(filter(x0, y)), ∀ y0. ¬ dups(filter(x0, y0)) ⊦ a ∈ y, a ∈ x0, dups(x0)
Used simplifier rules: filt-n: ⊦ ¬ a ∈ y → filter(a ' + x, y) = filter(x, y);%a: ⊦ (x + y) + z = x + y + z; from specification list