Theorems · Definition · combinatorics
Fintype.sumLeft
{α : Type u_4} → {β : Type u_5} → [Fintype (α ⊕ β)] → Fintype αGiven that α ⊕ β is a fintype, α is also a fintype. This is non-computable as it uses
that Sum.inl is an injection, but there's no clear inverse if α is empty.
- Defined in
- Mathlib.Data.Fintype.Card
- Cited by
- 0 results in Mathlib
- Foundations
- Depth 79 from the axioms · uses propext, Classical.choice, Quot.sound
- Assumes
- Fintype
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- Fintypestatement and proof · cited by 7,736
- Sum.inl_injectiveproof · cited by 39
- Fintype.ofInjectiveproof · cited by 3
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