English
A model realizes denselyOrderedSentence iff the domain is densely ordered.
Русский
Модель реализует denselyOrderedSentence тогда и только тогда, когда множество плотно упорядочено.
LaTeX
$$$ M \\models L.denselyOrderedSentence \\iff DenselyOrdered M $$$
Lean4
theorem realize_denselyOrdered_iff : M ⊨ L.denselyOrderedSentence ↔ DenselyOrdered M :=
by
simp only [denselyOrderedSentence, Sentence.Realize, Formula.Realize, BoundedFormula.realize_imp,
BoundedFormula.realize_all, Term.realize_lt, BoundedFormula.realize_ex, BoundedFormula.realize_inf]
refine ⟨fun h => ⟨fun a b ab => h a b ab⟩, ?_⟩
intro h a b ab
exact exists_between ab