| ⊦ prefixn(n + 1, x) ≠ [] ↔ x ≠ [] |
⊦ prefixn(n, x) = (n ≤ # x ⊃ firstn(n, x);x)
[Concretesimprules((Csimpnamedseq(prefixn,,, ⊦ prefixn(n, x) = (n ≤ # x ⊃ firstn(n, x);x)) Csimpnamedseq(nat,,succ-01, ⊦ m + 1 ≤ n ↔ m < n) Csimpnamedseq(nat-basic2,,c, ⊦ m + n = n + m) Csimpnamedseq(nat-basic2,,a, ⊦ (m + n0) + n1 = m + n0 + n1) Csimpnamedseq(nat,,le-num-06, n0 < n ⊦ ¬ m + (* n) ≤ (* n0)) Csimpnamedseq(list-data,,size-01, ⊦ # [] = 0)))]