| ⊦ filter(rmdup(x), y) = rmdup(filter(x, y)) |
∀ y. filter(rmdup(x0), y) = rmdup(filter(x0, y)) ⊦ filter(rmdup(a + x0), y) = rmdup(filter(a + x0, y))
Used simplifier rules: filt-e: ⊦ filter([], y) = [];%list freely generated by [], +;;%rmdup-e: ⊦ rmdup([]) = []; from specification list-dup