Cythonize GraphicMatroid

[gmou3]

A metamorphosis of graphic_matroid.py into graphic_matroid.pyx and graphic_matroid.pxd.
Things should be somewhat faster; test, e.g., the GraphicMatroid's _circuit function. An indirect and diluted test that shows improvement can be seen by running %time matroids.CompleteGraphic(8).circuits() (~half the time).

For the reviewer: The changes of this PR are only inside the matroids module. The rest come from #37835.

⌛ Dependencies

#37835: Deeper improvements of DisjointSet.

[github-actions]

Documentation preview for this PR (built with commit 9fda0f7; changes) is ready! 🎉
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[tscrim]

It might be good to look at the C code generated in performance critical sections to see if there are additional places where type casting and other such declarations could simplify the C code (and hence, increase performance). Although I am basically okay to include this in the current state and do other general improvements in later PRs. It is up to you.

[gmou3]

It might be good to look at the C code generated in performance critical sections to see if there are additional places where type casting and other such declarations could simplify the C code (and hence, increase performance). Although I am basically okay to include this in the current state and do other general improvements in later PRs. It is up to you.

I hadn't thought of doing that and I'll keep the idea in mind for future PRs.

[tscrim]

Okay, then let's get this in. It seems like the tester failures are unrelated, but it would be good to have them be run... I don't know how to kick it to run it again.

[gmou3]

Please don't kick it as it may further break things.
There are many errors indeed; alas, what a state of disrepair!

[mkoeppe]

I've repaired the CI, which complains:

sage -t --random-seed=109326302233194564031839857779385647036 src/sage/matroids/graphic_matroid.py
**********************************************************************
File "src/sage/matroids/graphic_matroid.py", line 490, in sage.matroids.graphic_matroid.GraphicMatroid._minor
Failed example:
    M._minor(deletions=frozenset([0,1,2]))
Exception raised:
    Traceback (most recent call last):
      File "/sage/src/sage/doctest/forker.py", line 714, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/sage/src/sage/doctest/forker.py", line 1146, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.matroids.graphic_matroid.GraphicMatroid._minor[1]>", line 1, in <module>
        M._minor(deletions=frozenset([Integer(0),Integer(1),Integer(2)]))
      File "sage/matroids/graphic_matroid.pyx", line 462, in sage.matroids.graphic_matroid.GraphicMatroid._minor
        cpdef _minor(self, contractions, deletions):
    TypeError: _minor() takes exactly 2 positional arguments (0 given)
**********************************************************************
File "src/sage/matroids/graphic_matroid.py", line 492, in sage.matroids.graphic_matroid.GraphicMatroid._minor
Failed example:
    M._minor(contractions=frozenset([0,1,2]))
Exception raised:
    Traceback (most recent call last):
      File "/sage/src/sage/doctest/forker.py", line 714, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/sage/src/sage/doctest/forker.py", line 11[46](https://github.com/sagemath/sage/actions/runs/8959227503/job/24712775461?pr=37839#step:12:47), in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.matroids.graphic_matroid.GraphicMatroid._minor[2]>", line 1, in <module>
        M._minor(contractions=frozenset([Integer(0),Integer(1),Integer(2)]))
      File "sage/matroids/graphic_matroid.pyx", line 462, in sage.matroids.graphic_matroid.GraphicMatroid._minor
        cpdef _minor(self, contractions, deletions):
    TypeError: _minor() takes exactly 2 positional arguments (1 given)
**********************************************************************

[tscrim]

Something is wrong with the CI. There is no more graphic_matroid.py file as it is changed to a .pyx file.

[mkoeppe]

Indeed, sorry for the noise.