| a ∈ y, ∀ y. filter(rmdup(x0), y) = rmdup(filter(x0, y)) ⊦ filter(rmdup(a ' + x0), y) = rmdup(a ' + filter(x0, y)) |
⊦ a ∈ x → rmdup(a ' + x) = rmdup(x)
¬ a ∈ filter(x0, y), a ∈ y, ∀ y. filter(rmdup(x0), y) = rmdup(filter(x0, y)) ⊦ filter(rmdup(a ' + x0), y) = rmdup(a ' + filter(x0, y))
a ∈ filter(x0, y), a ∈ y, ∀ y. filter(rmdup(x0), y) = rmdup(filter(x0, y)) ⊦ filter(rmdup(a ' + x0), y) = rmdup(filter(x0, y))
Used terms: filter(x0, y), a