mathlib
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feat(group/perm/sign): swap_adj_induction_on
- Defines the multilinear map that sends a tuple of elements of an algebra to their product.
- ~~Defines the typeclass
alternating_map
that extendsmultilinear_map
.~~ Superseded by #5102 - Proves some lemmas about permutations and lists that are necessary for (1) and (2), and some lemmas about permutations of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.
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.
I suspect the now-merged #4316 contains some pieces and lemma names that can be reused and copied here
I went ahead and fixed the merge conflicts, and removed all the proofs that now exist elsewhere in mathlib.
I've renamed this PR, since all the algebra pieces have been merged elsewhere.