leninv(nσ) = ⌜n0⌝ , n0 = 0, ⌜n⌝ < # nσ, n0 < nσ[n], stutf(nσ) ⊦
leninv(nσ) = ⌜n0⌝ , n0 = n1 +1, ⌜n⌝ < # nσ, n0 < nσ[n], stutf(nσ) ⊦
Used simplifier rules: nat freely generated by 0, +1;;