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