⊦ nf from m from n = nf from m + n
Used simplifier rules: from-inf: ⊦ ⌜nf⌝ from n = ⌜nf from n⌝ ;%size-inf: ⊦ # ⌜nf⌝ = ∞;% ⊦ ¬ ∞ < n∞; (s)% ⊦ ⌜nf⌝ = ⌜nf0⌝ ↔ nf = nf0; (s)