| ⊦ (σ to n) + σ0 from n1 + n = σ0 from n1, # σ0 < ⌜n1⌝ , # σ < ⌜n⌝ |
⊦ σ0 = σ1 ↔ # σ0 = # σ1 ∧ (∀ n. ⌜n⌝ < # σ0 → σ0[n] = σ1[n])
⊦ #((σ to n) + σ0 from n1 + n) = #(σ0 from n1) ∧ (∀ n0. ⌜n0⌝ < #((σ to n) + σ0 from n1 + n) → ((σ to n) + σ0 from n1 + n)[n0] = (σ0 from n1)[n0]), # σ0 < ⌜n1⌝ , # σ < ⌜n⌝
Used terms: σ0 from n1, (σ to n) + σ0 from n1 + n