| ⊦ x = firstn(n, x) + a ' + y → firstn(n + 1, x) = firstn(n, x) + a ' |
x = firstn(n, x) + a ' + y ⊦ x.first ' + firstn(n, x.rest) = firstn(n, x) + a '
Used simplifier rules: firstN-rec: ⊦ firstn(n + 1, x) = x.first + firstn(n, x.rest);%c: ⊦ m + n = n + m; from specification nat-basic2%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic2%c: ⊦ a + x = a ' + x; from specification list