#11670: fix number fields being unique parents -- this got broken over the years
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Reporter: was | Owner: davidloeffler
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.2
Component: number fields | Resolution:
Keywords: | Merged in:
Authors: Julian Rueth | Reviewers: Simon King
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/saraedum/ticket/11670 | cab3fe1eb4c425f0028b221494f95a03199f2936
Dependencies: | Stopgaps:
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Changes (by {'newvalue': u'Julian Rueth', 'oldvalue': u'William Stein'}):
* status: needs_work => needs_review
* author: William Stein => Julian Rueth
Comment:
Pickling of old and new number fields should work now. I found these
issues though.
Absolute number fields used to forget about their structure, this is fixed
now (of course the structure can not be recovered for old pickles):
{{{
sage: K.<a> = QuadraticField(2)
sage: L.<b> = K.change_names()
sage: M=loads(dumps(L))
sage: M.structure() # old behaviour
(Ring Coercion endomorphism of Number Field in b with defining polynomial
x^2 - 2,
Ring Coercion endomorphism of Number Field in b with defining polynomial
x^2 - 2)
sage: L.structure() # this is what M.structure() returns now
(Isomorphism given by variable name change map:
From: Number Field in b with defining polynomial x^2 - 2
To: Number Field in a with defining polynomial x^2 - 2,
Isomorphism given by variable name change map:
From: Number Field in a with defining polynomial x^2 - 2
To: Number Field in b with defining polynomial x^2 - 2)
}}}
Relative number fields also used to forget about their structure. Since I
have not touched the pickling of relative number fields, I would rather
put this into a separate ticket:
{{{
sage: sage: Z = var('Z')
sage: sage: K.<w> = NumberField(Z^3 + Z + 1)
sage: sage: L.<z> = K.extension(Z^3 + 2)
sage: sage: M.<u,v> = L.change_names()
sage: sage: M.structure()
(Isomorphism given by variable name change map:
From: Number Field in u with defining polynomial x^3 + 2 over its base
field
To: Number Field in z with defining polynomial Z^3 + 2 over its base
field,
Isomorphism given by variable name change map:
From: Number Field in z with defining polynomial Z^3 + 2 over its base
field
To: Number Field in u with defining polynomial x^3 + 2 over its base
field)
sage: sage: M = loads(dumps(M))
sage: sage: M.structure()
(Ring Coercion endomorphism of Number Field in u with defining polynomial
x^3 + 2 over its base field,
Ring Coercion endomorphism of Number Field in u with defining polynomial
x^3 + 2 over its base field)
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/11670#comment:21>
Sage <http://www.sagemath.org>
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