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feat(group/perm/sign): swap_adj_induction_on

Open zhangir-azerbayev opened this issue 4 years ago • 4 comments

  1. Defines the multilinear map that sends a tuple of elements of an algebra to their product.
  2. ~~Defines the typeclass alternating_map that extends multilinear_map.~~ Superseded by #5102
  3. Proves some lemmas about permutations and lists that are necessary for (1) and (2), and some lemmas about permutations of fin n that will be useful for formalizing exterior algebras.

This PR is essentially a number of lemmas and constructions I wrote for the exterior_algebra branch stated at the appropriate level of generality.

A particular area where I could use some help is deciding where long proofs should be split into several shorter lemmas.

zhangir-azerbayev avatar Aug 14 '20 00:08 zhangir-azerbayev

This will not build against master due to changes in fin. I pushed some changes to https://github.com/leanprover-community/mathlib/tree/exterior_algebra which make the necessary fixes, they might help you make the fixes here.

eric-wieser avatar Sep 25 '20 12:09 eric-wieser

I suspect the now-merged #4316 contains some pieces and lemma names that can be reused and copied here

eric-wieser avatar Oct 20 '20 16:10 eric-wieser

I went ahead and fixed the merge conflicts, and removed all the proofs that now exist elsewhere in mathlib.

eric-wieser avatar Nov 23 '20 14:11 eric-wieser

I've renamed this PR, since all the algebra pieces have been merged elsewhere.

eric-wieser avatar Dec 01 '20 16:12 eric-wieser