| ∀ y, a. filter(rmdup(x0), y -1l a) = filter(rmdup(x0), y) ∨ a ∈ x0 ⊦ a0 ∈ y -1l a, a = a0, filter(a0 ' + rmdup(x0), y -1l a) = filter(a0 ' + rmdup(x0), y), a0 ∈ x0, a ∈ x0 |
∀ y, a. filter(rmdup(x0), y -1l a) = filter(rmdup(x0), y) ∨ a ∈ x0 ⊦ a = a0, filter(rmdup(x0), y -1l a) = filter(rmdup(x0), y), a0 ∈ x0, a ∈ x0, a0 ∈ y
Used simplifier rules: filt-n: ⊦ ¬ a ∈ y → filter(a ' + x, y) = filter(x, y);%del1-in: ⊦ a ≠ b → (a ∈ x -1l b ↔ a ∈ x); from specification list-del%a: ⊦ (x + y) + z = x + y + z; from specification list