feat(data/fintype): injective_iff_surjective #240
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digama0
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Aug 7, 2018
data/fintype.lean
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| injective f ↔ surjective f := | ||
| have injective (e.symm ∘ f) ↔ surjective (e.symm ∘ f), from fintype.injective_iff_surjective, | ||
| ⟨λ hinj, by have := surjective_comp e.bijective.2 (this.1 (injective_comp e.symm.bijective.1 hinj)); | ||
| simpa [function.comp] using this, |
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simpa using this can be shortened to just simpa; have := term; simpa can be rewritten as simpa using term.
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