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