refactor(algebra/field): partially migrate to bundled homs #1999
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jcommelin
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Feb 17, 2020
| λ x0 h, one_ne_zero $ calc | ||
| 1 = f (x * x⁻¹) : by rw [mul_inv_cancel x0, map_one f] | ||
| ... = 0 : by rw [map_mul f, h, zero_mul]⟩ | ||
| ⟨mt $ λ h, h.symm ▸ f.map_zero, |
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Should all these map_* lemmas be simp?
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I don't know. I guess they were not marked as simp because looking for is_ring_hom is expensive.
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So now, when we bundle, we can (and should?)
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| lemma map_div' (h : y ≠ 0) : f (x / y) = f x / f y := | ||
| (map_mul f).trans $ congr_arg _ $ map_inv' f h | ||
| (f.map_mul _ _).trans $ congr_arg _ $ f.map_inv' h |
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@digama0 Is it time to make changes to Lean core, and fix the definition of field and division ring?
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Fine with me, although I would prefer to delegate the scheduling of the first non-backward compatible lean release to @robertylewis and @cipher1024 .
ChrisHughes24
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…r-community#1999) * refactor(algebra/field): partially migrate to bundled homs * Add a few `@[simp]` attrs Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
anrddh
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May 16, 2020
…r-community#1999) * refactor(algebra/field): partially migrate to bundled homs * Add a few `@[simp]` attrs Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
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