| ∃ a, x0, y0, z. y = x0 + (a + (y0 + (a + z))), x ⊆m y, ∀ a. #oc(a, y) ≤ #oc(a, x) ⊦ dups(x) |
x ⊆m x0 + a ' + y0 + a ' + z, ∀ a0. #oc(a0, x0) + #oc(a0, a ') + #oc(a0, y0) + #oc(a0, a ') + #oc(a0, z) ≤ #oc(a0, x) ⊦ dups(x)
Used simplifier rules: ocappend: ⊦ #oc(a, x + y) = #oc(a, x) + #oc(a, y);%a: ⊦ (x + y) + z = x + y + z; from specification list%c: ⊦ a + x = a ' + x; from specification list