| ⊦ (∃ n0. eq-entry(n0, none) ∈ q ∨ eq-entry(n0, none) = eq-entry(n, lref0)) ↔ (∃ n. eq-entry(n, none) ∈ q), none = lref0 |
∃ n0. eq-entry(n0, none) ∈ q ∨ eq-entry(n0, none) = eq-entry(n, lref0) ⊦ none = lref0, ∃ n. eq-entry(n, none) ∈ q
∃ n. eq-entry(n, none) ∈ q ⊦ none = lref0, ∃ n0. eq-entry(n0, none) ∈ q ∨ eq-entry(n0, none) = eq-entry(n, lref0)