| ⊦ perm(x, mklist(a, n)) ↔ x = mklist(a, n) |
∀ x, a. perm(x, mklist(a, n0)) ↔ x = mklist(a, n0) ⊦ perm(x, mklist(a, n0 +1)) ↔ x = mklist(a, n0 +1)
Used simplifier rules: empty: ⊦ perm(x, []) ↔ x = [];%perm-e: ⊦ perm([], []);%nat freely generated by 0, +1;;%mk-zero: ⊦ mklist(a, 0) = []; from specification list-last