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feat(order): finite preorders have finite order dimension#92

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kernelpanic888:codex/finite-dimensional-order-of-finite-v3
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feat(order): finite preorders have finite order dimension#92
kernelpanic888 wants to merge 1 commit into
SnirBroshi:masterfrom
kernelpanic888:codex/finite-dimensional-order-of-finite-v3

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@kernelpanic888

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Add an instance showing that every finite nonempty preorder has finite order dimension.


Addresses the first proposed result in #90.

The Nonempty α assumption is necessary: FiniteDimensionalOrder α implies Nonempty α, while Fin 0 is finite and has a preorder.

The proof assumes an arbitrarily long strict chain, chooses one of length Fintype.card α, and contradicts the existing bound LTSeries.length_lt_card.

Validation:

  • lake build Mathlib.Order.RelSeries
  • focused Fin 0 counterexample
  • #print axioms Finite.to_finiteDimensionalOrder: propext, Classical.choice, Quot.sound

Add instance for finite dimensional order in finite nonempty preorders.
@SnirBroshi

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Hello! Who are you? Is this LLM generated?

The Nonempty α assumption is necessary

Thanks! Fixed

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