| ⊦ ⌜nf⌝ = ⌜hd(⌜nf⌝ ) '⌝ + tl(⌜nf⌝ ), ⌜nf⌝ = [] |
⊦ ⌜nf⌝ = ⌜nf(0) '⌝ + ⌜λ n. nf(n + 1)⌝
Used simplifier rules: hd-inf: ⊦ hd(⌜nf⌝ ) = nf(0);%tl-inf: ⊦ tl(⌜nf⌝ ) = ⌜λ n. nf(n +1)⌝ ;%fun-nonempty: ⊦ [] ≠ ⌜nf⌝ ;%succ: ⊦ m +1 = m + 1; from specification nat-basic2