Valuation on power series and Laurent series #39517

xcaruso · 2025-02-13T17:33:02Z

We implement the method valuation on the rings of power series and Laurent series.

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xcaruso · 2025-02-13T17:33:37Z

I still have a problem with categories that I do not understand. Please tell me if you have some insight.

saraedum · 2025-02-13T17:54:38Z

src/sage/rings/series_valuation.py

+
+from sage.rings.valuation.valuation import DiscreteValuation
+
+class SeriesValuation(DiscreteValuation):


Have you considered making this a UniqueRepresentation? Then you can throw out _eq_ and __reduce__ from your implementation.

Yes, I tried it (not so hard). But got an error that I did not really understand (something with metaclasses).

Ah, that's annoying. Then you need to add a silly little factory.

Let me know if you need any support here (I can add it if you want me to.)

I don't think you need a factory, but you probably need the right metaclass, which I think is from sage.misc.inherit_comparison import InheritComparisonClasscallMetaclass.

mantepse · 2025-02-13T17:54:55Z

could you add this simultaneously to the lazy power / Laurent series?

or should this be actually a method in a category?

saraedum · 2025-02-13T17:55:42Z

src/sage/rings/laurent_series_ring.py

+        valuation_space = DiscretePseudoValuationSpace(self)
+        return SeriesValuation(valuation_space)


You want to do valuation_space.__make_element_class__(SeriesValuation)(valuation_space) to get the category right.

src/sage/rings/series_valuation.py

xcaruso · 2025-02-13T17:58:26Z

could you add this simultaneously to the lazy power / Laurent series?

Sure, I will do it.

saraedum · 2025-02-13T18:10:09Z

src/sage/rings/series_valuation.py

+            sage: v  # indirect doctest
+            t-adic valuation
+        """
+        return "%s-adic valuation" % self.domain().uniformizer()


Suggested change

return "%s-adic valuation" % self.domain().uniformizer()

return "%s-adic valuation" % self.uniformizer()

I think it would be good to implement uniformizer() on the level of valuation.

Actually, once the "category" test above passes, more tests coming from the category of discrete valuations are going to fail, namely that you are missing a bunch of methods: uniformizer, reduce, lift, residue_field.

github-actions · 2025-02-13T18:16:02Z

Documentation preview for this PR (built with commit f31283a; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

xcaruso · 2025-02-13T20:49:26Z

Thanks for your help. I think that everything is working correctly now.

saraedum · 2025-02-14T08:47:27Z

src/sage/rings/series_valuation.py

+
+    def create_object(self, version, key, **extra_args):
+        r"""
+        Create a unique key identifying the valuation of ``R``.


Actually this creates the object. That's the docstring for the other method I guess.

saraedum · 2025-02-14T08:48:10Z

src/sage/rings/series_valuation.py

+SeriesValuation = SeriesValuationFactory("sage.rings.series_valuation.SeriesValuation")
+
+
+class SeriesValuation_base(DiscreteValuation):


Maybe _generic since there's nobody inheriting from this. Base sounds like abstract base to me (just a suggestion. Keep it if you want.)

saraedum · 2025-02-14T08:51:37Z

doctests fail with:

File "src/sage/rings/series_valuation.py", line 30, in sage.rings.series_valuation.SeriesValuationFactory
Failed example:
    v = R.valuation()
Exception raised:
    Traceback (most recent call last):
      File "/home/runner/miniconda3/envs/sage-dev/lib/python3.11/site-packages/sage/doctest/forker.py", line 728, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/runner/miniconda3/envs/sage-dev/lib/python3.11/site-packages/sage/doctest/forker.py", line 1152, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.rings.series_valuation.SeriesValuationFactory[1]>", line 1, in <module>
        v = R.valuation()
            ^^^^^^^^^^^^^
      File "/home/runner/miniconda3/envs/sage-dev/lib/python3.11/site-packages/sage/rings/power_series_ring.py", line 672, in valuation
        from sage.rings.series_valuation import SeriesValuation
    ModuleNotFoundError: No module named 'sage.rings.series_valuation'

fchapoton · 2025-02-21T15:10:16Z

je me suis permis de corriger les problemes du "linter".

Attention à bien faire "git pull" avant de travailler a nouveau sur la branche.

valuation of power series and Laurent series

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xcaruso added the sd128 tickets of Sage Days 128 Le Teich label Feb 13, 2025

xcaruso requested a review from saraedum February 13, 2025 17:33

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saraedum reviewed Feb 13, 2025

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implement a factory and required methods

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implementation on lazy Laurent series rings

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fix various things

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fchapoton added the c: commutative algebra label Feb 21, 2025

fix the linter in series_valuation.py

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Valuation on power series and Laurent series #39517

Valuation on power series and Laurent series #39517

xcaruso commented Feb 13, 2025

xcaruso commented Feb 13, 2025

saraedum Feb 13, 2025

xcaruso Feb 13, 2025

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mantepse commented Feb 13, 2025

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saraedum Feb 14, 2025

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saraedum commented Feb 14, 2025

fchapoton commented Feb 21, 2025 •

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		from sage.rings.valuation.valuation import DiscreteValuation

		class SeriesValuation(DiscreteValuation):

		valuation_space = DiscretePseudoValuationSpace(self)
		return SeriesValuation(valuation_space)

	return "%s-adic valuation" % self.domain().uniformizer()
	return "%s-adic valuation" % self.uniformizer()

		SeriesValuation = SeriesValuationFactory("sage.rings.series_valuation.SeriesValuation")


		class SeriesValuation_base(DiscreteValuation):

Valuation on power series and Laurent series #39517

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Valuation on power series and Laurent series #39517

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xcaruso commented Feb 13, 2025

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