⊦ ⌜x⌝ + ⌜nf⌝ = ⌜λ n. (n < # x ⊃ x[n];nf(n - # x))⌝
⌜λ n. (n < # x ⊃ x[n];nf(n - # x))⌝ = ⌜x⌝ + ⌜nf0⌝ ⊦ nf = nf0
Used terms: nf, x