English
If f: α → β is strictly monotone and α is infinite-dimensional, then β is infinite-dimensional.
Русский
Если f: α → β строго монотонна и α бесконечно размерна, то β также бесконечно размерен.
LaTeX
$$$\\forall f:\\,\\alpha \\to \\beta,\\; (\\text{StrictMono}(f)) \\land [InfiniteDimensionalOrder(\\alpha)] \\rightarrow InfiniteDimensionalOrder(\\beta)$$$
Lean4
/-- If `f : α → β` is a strictly monotonic function and `α` is an infinite-dimensional type then so
is `β`. -/
theorem infiniteDimensionalOrder_of_strictMono [Preorder α] [Preorder β] (f : α → β) (hf : StrictMono f)
[InfiniteDimensionalOrder α] : InfiniteDimensionalOrder β :=
⟨fun n ↦ ⟨(LTSeries.withLength _ n).map f hf, LTSeries.length_withLength α n⟩⟩