# σ = ⌜n⌝ ⊦ # σ = ∞, σ + σ⊥ = σ⊥ ↔ σ = σ⊥ to n
[Concretesimprules((Csimpelim( ⊦ n∞ ≠ ∞ → (n = n∞.n ↔ n∞ = ⌜n⌝ )))), Extraterms((# σm))]