Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

implement natural morphism from cl(f²D) to cl(D) #37074

Merged

Conversation

yyyyx4
Copy link
Member

@yyyyx4 yyyyx4 commented Jan 16, 2024

...for class groups of binary quadratic forms, which we have since #36184.

This map is defined by finding a class representative $[a,b,c]$ for which $f^2 \mid a$ (and $f \mid b$) and then applying the substitution $x \mapsto x/f$. In the code, we do it in prime steps, since that makes finding a suitable representative a little easier.

This can be used, among other things, for determining the kernel of the surjection $\mathrm{cl}(f^2D) \twoheadrightarrow \mathrm{cl}(D)$.

src/sage/quadratic_forms/bqf_class_group.py Outdated Show resolved Hide resolved
src/sage/quadratic_forms/bqf_class_group.py Outdated Show resolved Hide resolved
src/sage/quadratic_forms/bqf_class_group.py Outdated Show resolved Hide resolved
src/sage/quadratic_forms/bqf_class_group.py Outdated Show resolved Hide resolved
Copy link

Documentation preview for this PR (built with commit b75a9a4; changes) is ready! 🎉

Copy link
Collaborator

@tscrim tscrim left a comment

Choose a reason for hiding this comment

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

Thanks. LGTM.

@yyyyx4
Copy link
Member Author

yyyyx4 commented Jan 19, 2024

Thank you!

@vbraun vbraun merged commit e3fd6ec into sagemath:develop Jan 22, 2024
14 of 21 checks passed
@yyyyx4 yyyyx4 deleted the public/bqfclassgroup_quotient_morphisms branch January 22, 2024 01:05
vbraun pushed a commit to vbraun/sage that referenced this pull request Feb 7, 2024
…documentation

    
The possibility to pass discriminants to the constructor instead of
`BQFClassGroup` objects was present for an earlier version of sagemath#37074,
but it was removed during review. However, it seems I forgot to update
the docstring accordingly.
    
URL: sagemath#37233
Reported by: Lorenz Panny
Reviewer(s): Travis Scrimshaw
vbraun pushed a commit to vbraun/sage that referenced this pull request Feb 11, 2024
…documentation

    
The possibility to pass discriminants to the constructor instead of
`BQFClassGroup` objects was present for an earlier version of sagemath#37074,
but it was removed during review. However, it seems I forgot to update
the docstring accordingly.
    
URL: sagemath#37233
Reported by: Lorenz Panny
Reviewer(s): Travis Scrimshaw
@mkoeppe mkoeppe added this to the sage-10.3 milestone Mar 7, 2024
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Projects
None yet
Development

Successfully merging this pull request may close these issues.

None yet

4 participants