English
If f is monotone, then f(min S) = min (image f of S).
Русский
Если f монотонна, то f(min S) = min образа f(S).
LaTeX
$$$f(\\min' S) = \\min'(\\mathrm{image}(f, S))$$$
Lean4
/-- A version of `Finset.min'_image` with LHS and RHS reversed.
Also, this version assumes that `s` is nonempty, not its image. -/
theorem _root_.Monotone.map_finset_min' [LinearOrder β] {f : α → β} (hf : Monotone f) {s : Finset α} (h : s.Nonempty) :
f (s.min' h) = (s.image f).min' (h.image f) :=
.symm <| min'_image hf ..