Laurent power series fail unique representation

[videlec]

sage: L.<q> = LaurentSeriesRing(QQ)
sage: LaurentSeriesRing(QQ, 'q') is L
False

to be compared with

sage: R.<q> = PolynomialRing(QQ)
sage: PolynomialRing(QQ, 'q') is R
True

We also fix

sage: LaurentSeriesRing(Zmod(4), 'x').category()
Category of fields

We also remove the classes LaurentSeriesRing_generic, LaurentSeriesRing_domain, LaurentSeriesRing_field in favor of a unique LaurentSeriesRing.

Component: algebra

Author: Vincent Delecroix

Branch/Commit: bcf577d

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/24420

[videlec]

Author: Vincent Delecroix

[videlec]

New commits:

f779b10

24420: clean laurent series

[videlec]

Branch: u/vdelecroix/24420

[videlec]

Commit: f779b10

[sagetrac-git]

Changed commit from f779b10 to 1adb84c

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

1adb84c

24420: clean laurent series

[sagetrac-git]

Changed commit from 1adb84c to cdf836a

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

cdf836a

24420: clean laurent series

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

34769e1

24420: clean laurent series

[sagetrac-git]

Changed commit from cdf836a to 34769e1

[videlec]

comment:8

rebased on 8.2.beta2

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:9

Since you are going to do the category imports in the __init__ (which I'm not 100% in agreement with), I would make it in as small as scope as possible:

         from sage.categories.rings import Rings
         from sage.categories.integral_domains import IntegralDomains
         from sage.categories.fields import Fields
-        from sage.categories.complete_discrete_valuation import (
-                CompleteDiscreteValuationRings, CompleteDiscreteValuationFields)
 
         base_ring = power_series.base_ring()
         if base_ring in Fields():
+            from sage.categories.complete_discrete_valuation import CompleteDiscreteValuationFields
             category = CompleteDiscreteValuationFields()
         elif base_ring in IntegralDomains():
             category = IntegralDomains()
         elif base_ring in Rings().Commutative():
             category = Rings().Commutative()
         else:
             raise ValueError('unrecognized base ring')

Also, don't we want to use names=power_series.variable_names() in case we (eventually support) have multiple variable names. Otherwise LGTM.

[videlec]

comment:10

Replying to @tscrim:

Since you are going to do the category imports in the __init__ (which I'm not 100% in agreement with)

Why? I am happy to move them at the module scope if it is a better practice.

[tscrim]

comment:11

Replying to @videlec:

Replying to @tscrim:

Since you are going to do the category imports in the __init__ (which I'm not 100% in agreement with)

Why? I am happy to move them at the module scope if it is a better practice.

It slows down the construction of the ring.

[sagetrac-git]

Changed commit from 34769e1 to fd34a95

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

fd34a95

24420: move imports / name -> names

[videlec]

comment:13

done

[tscrim]

comment:14

Thanks. One last little thing: you don't use CompleteDiscreteValuationRings.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

bcf577d

24420: move imports / name -> names

[sagetrac-git]

Changed commit from fd34a95 to bcf577d

[videlec]

comment:16

Indeed!

[tscrim]

comment:17

Thanks.

[vbraun]

Changed branch from u/vdelecroix/24420 to bcf577d