⊦ ⌜nf from n⌝ = ⌜nf(n) '⌝ + ⌜nf from n + 1⌝
Used simplifier rules: from-inf: ⊦ ⌜nf⌝ from n = ⌜nf from n⌝ ;%sel-inf: ⊦ ⌜nf⌝ [n] = nf(n);%size-inf: ⊦ # ⌜nf⌝ = ∞;% ⊦ ⌜m⌝ < ∞; (s)