| eq-entry(n, lref) ∈ q, ∀ lref. lref ∈ q.lebrefs ↔ (∃ n. eq-entry(n, lref) ∈ q) ∧ lref ≠ none ⊦ eq-entry(n, lref) = eq-entry(m, none), lref = none, lref ∈ q.lebrefs, none ∈ q.lebrefs |
lref ∈ q.lebrefs ↔ (∃ n. eq-entry(n, lref) ∈ q) ∧ lref ≠ none, eq-entry(n, lref) ∈ q, ∀ lref. lref ∈ q.lebrefs ↔ (∃ n. eq-entry(n, lref) ∈ q) ∧ lref ≠ none ⊦ eq-entry(n, lref) = eq-entry(m, none), lref = none, none ∈ q.lebrefs, lref ∈ q.lebrefs
Used terms: lref