| ⊦ lastn(n + 1, x + a ') = lastn(n, x) + a ' |
Used simplifier rules: lastN-rec: ⊦ lastn(n + 1, x) = lastn(n, x.butlast) + x.last;%app-01: ⊦ x + y = x + z ↔ y = z; from specification list%c: ⊦ m + n = n + m; from specification nat-basic2%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic2%Last: ⊦ x + a = x + a '; from specification list%butlast-def: ⊦ (x + a ').butlast = x; from specification list-last%a: ⊦ (x + y) + z = x + y + z; from specification list%last-def: ⊦ (x + a ').last = a; from specification list-last