| ⊦ Σ(n, λ k. nf0(k) + nf1(k)) = Σ(n, nf0) + Σ(n, nf1) |
∀ nf0, nf1. Σ(n0, λ k. nf0(k) + nf1(k)) = Σ(n0, nf0) + Σ(n0, nf1) ⊦ Σ(n0 +1, λ k. nf0(k) + nf1(k)) = Σ(n0 +1, nf0) + Σ(n0 +1, nf1)
Used simplifier rules: sum-base: ⊦ Σ(0, nf) = 0;%nat freely generated by 0, +1;;%add-a: ⊦ i + j + i0 = (i + j) + i0; from specification int-basic2%add-c: ⊦ i + j = j + i; from specification int-basic2