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feat(mathematics): add the degree-wise linear universal property of the symmetric algebra - #1468

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feat(mathematics): add the degree-wise linear universal property of the symmetric algebra#1468
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@nateabr nateabr commented Jul 28, 2026

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Adds symmetric multilinear maps, symmetric-algebra monomials, and the degree-wise linear universal property of the symmetric algebra.

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nateabr marked this pull request as ready for review July 28, 2026 10:19
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Thank you for this PR, which will now be reviewed. If submitting to ./Physlib or ./QuantumInfo, please see our review guidelines if you are not familiar with the process. You should expect a back and forth with a reviewer before your PR is merged. See also that link for how to add appropriate labels to your PR. The PR will also go through a number of automated checks. You can learn more about these here, including how to run them locally.

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@nateabr nateabr added the t-mathematics Mathematics label Jul 28, 2026

/-!
# Symmetric monomials and the lift out of the symmetric algebra

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Is this also from a Mathlib PR, if so I think we should put right at the top of the doc-string, what PR and who the author is.

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I added the author to symmetricmap.lean as that was from a mathlib PR, this file was not from a mathlib PR though

@jstoobysmith jstoobysmith added the awaiting-author A reviewer has asked the author a question or requested changes label Jul 28, 2026
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nateabr commented Jul 28, 2026

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-awaiting-author

@github-actions github-actions Bot removed the awaiting-author A reviewer has asked the author a question or requested changes label Jul 28, 2026
variable (f : ∀ n, SymmetricMap R M N (Fin n))

/-- The linear map on the tensor algebra assembled from the degreewise symmetric maps. -/
private noncomputable def Lhat : TensorAlgebra R M →ₗ[R] N :=

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Is there an analogy for this to ExteriorAlgebra? I'm wondering about the choice of name


/-- The largest ring congruence on which `Lhat f` is constant: it relates `u` and `w` when
`Lhat f (a * u * b) = Lhat f (a * w * b)` for all `a` and `b`. -/
private def Qcon : RingCon (TensorAlgebra R M) where

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Likewise, wondering about this choice of name.

@jstoobysmith jstoobysmith self-assigned this Jul 28, 2026
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