| ax.toSet | m = ∅ ⊦ prefixn(n, ax).toSet | m = ∅ |
ax.toSet | m = ∅ ⊦ #(prefixn(n, ax).toSet | m) = 0, prefixn(n, ax).toSet | m = ∅
Used simplifier rules: size-zero: ⊦ # as ≠ 0 → as ≠ ∅; (forward) from specification set-basic[node-store]%size-zero-01: ⊦ as ≠ ∅ → # as ≠ 0; (forward) from specification set-basic[node-store]