English
The Birkhoff embedding into inf-irreducible upper sets maps a to (Ici a, infIrred ICI a).
Русский
Встраивание Биркгоффа в InfIrred верхних множеств отправляет a в (Ici a, infIrred ICI a).
LaTeX
$$infIrredUpperSet : α ↪o { s : UpperSet α // InfIrred s }$$
Lean4
/-- The **Birkhoff Embedding** of a finite partial order as inf-irreducible elements in its
lattice of lower sets. -/
def infIrredUpperSet : α ↪o { s : UpperSet α // InfIrred s }
where
toFun a := ⟨Ici a, infIrred_Ici _⟩
inj' _ := by simp
map_rel_iff' := by simp