| a ∈ filter(a0 ' + x0, y), a0 ∈ y, ∀ a, y. a ∈ filter(x0, y) → a ∈ y ⊦ a ∈ y |
a0 ∈ y, a ∈ filter(x0, y), ∀ a, y. a ∈ filter(x0, y) → a ∈ y ⊦ a ∈ y
Used simplifier rules: filt-y: ⊦ a ∈ y → filter(a ' + x, y) = a ' + filter(x, y);% ⊦ a ∈ b ' ↔ a = b; (s)% ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s)%a: ⊦ (x + y) + z = x + y + z; from specification list