English
If every J ∈ boxes is below I, then the constructed prepartition is below or equal to π.
Русский
Если каждый J ∈ boxes ниже I, то сконструированное предразбиение ниже или равно π.
LaTeX
$$$ ofWithBot boxes \\; le\_of\\_mem \\; pairwise\\_disjoint ≤ π $$$
Lean4
theorem ofWithBot_le {boxes : Finset (WithBot (Box ι))} {le_of_mem : ∀ J ∈ boxes, (J : WithBot (Box ι)) ≤ I}
{pairwise_disjoint : Set.Pairwise (boxes : Set (WithBot (Box ι))) Disjoint}
(H : ∀ J ∈ boxes, J ≠ ⊥ → ∃ J' ∈ π, J ≤ ↑J') : ofWithBot boxes le_of_mem pairwise_disjoint ≤ π :=
by
have : ∀ J : Box ι, ↑J ∈ boxes → ∃ J' ∈ π, J ≤ J' := fun J hJ => by
simpa only [WithBot.coe_le_coe] using H J hJ WithBot.coe_ne_bot
simpa [ofWithBot, le_def]