⊦ σ = σ2 ↔ # σ = # σ2 ∧ (∀ n. ⌜n⌝ < # σ → σ[n] = σ2[n])
⊦ # σ = ∞, # ⌜σ.buf⌝ = # σ ∧ (∀ n. ⌜n⌝ < # ⌜σ.buf⌝ → ⌜σ.buf⌝ [n] = σ[n])
Used terms: σ, ⌜σ.buf⌝