Skip to content

feat: port RingTheory.Polynomial.Quotient#3292

Closed
Ruben-VandeVelde wants to merge 17 commits intomasterfrom
port/RingTheory.Polynomial.Quotient
Closed

feat: port RingTheory.Polynomial.Quotient#3292
Ruben-VandeVelde wants to merge 17 commits intomasterfrom
port/RingTheory.Polynomial.Quotient

Conversation

@Ruben-VandeVelde
Copy link
Copy Markdown
Contributor


Open in Gitpod

Mathbin -> Mathlib
fix certain import statements
move "by" to end of line
add import to Mathlib.lean
@Ruben-VandeVelde Ruben-VandeVelde added help-wanted The author needs attention to resolve issues mathlib-port This is a port of a theory file from mathlib. labels Apr 5, 2023
@jjaassoonn
Copy link
Copy Markdown
Collaborator

noncomputable def quotientSpanXSubCAlgEquivAux2 (x : R) :
    (R[X] ⧸ (RingHom.ker (aeval x).toRingHom : Ideal R[X])) ≃ₐ[R] R :=
let e := RingHom.quotientKerEquivOfRightInverse (by
    intro x; exact eval_C : Function.RightInverse (fun a : R => (C a : R[X])) (@aeval R R _ _ _ x))
{ e with commutes' := fun r => e.apply_symm_apply r }

noncomputable def quotientSpanXSubCAlgEquivAux1 (x : R) :
  (R[X] ⧸ Ideal.span {X - C x}) ≃ₐ[R] (R[X] ⧸ (RingHom.ker (aeval x).toRingHom : Ideal R[X])) :=
@Ideal.quotientEquivAlgOfEq R R[X] _ _ _ _ _ (ker_evalRingHom x).symm

noncomputable def quotientSpanXSubCAlgEquiv (x : R) :
    (R[X] ⧸ Ideal.span ({X - C x} : Set R[X])) ≃ₐ[R] R :=
  (quotientSpanXSubCAlgEquivAux1 x).trans (quotientSpanXSubCAlgEquivAux2 x)

This works but introduces two sub definitions, so I am not sure if I should push it?

@Ruben-VandeVelde
Copy link
Copy Markdown
Contributor Author

Feel free to push

(R[X] ⧸ Ideal.span {X - C x}) ≃ₐ[R] (R[X] ⧸ (RingHom.ker (aeval x).toRingHom : Ideal R[X])) :=
@Ideal.quotientEquivAlgOfEq R R[X] _ _ _ _ _ (ker_evalRingHom x).symm

noncomputable def quotientSpanXSubCAlgEquiv (x : R) :
Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

As mentioned above, this has been splited into two sub-constructions which may or may not be ideal

@kim-em
Copy link
Copy Markdown
Contributor

kim-em commented May 16, 2023

Closing in favour of #3932.

@kim-em kim-em closed this May 16, 2023
bors bot pushed a commit that referenced this pull request May 17, 2023
Coming from #3292


- [x] depends on: #3414

[![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/from-referrer/)


Co-authored-by: Ruben Van de Velde <65514131+Ruben-VandeVelde@users.noreply.github.com>
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
Co-authored-by: Kevin Buzzard <k.buzzard@imperial.ac.uk>
Co-authored-by: int-y1 <jason_yuen2007@hotmail.com>
Co-authored-by: Parcly Taxel <reddeloostw@gmail.com>
@int-y1 int-y1 deleted the port/RingTheory.Polynomial.Quotient branch July 1, 2023 22:24
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

help-wanted The author needs attention to resolve issues mathlib-port This is a port of a theory file from mathlib.

Projects

None yet

Development

Successfully merging this pull request may close these issues.

5 participants