#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_info
Priority: major | Milestone: sage-4.7.2
Component: number fields | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by SimonKing):
I see a potential work-around. In my example, we have
{{{
sage: N = NumberField(x^12 - 4*x^11 + 6*x^10 - 5*x^9 + 5*x^8 - 9*x^7 +
21*x^6 - 9*x^5 + 5*x^4 - 5*x^3 + 6*x^2 - 4*x + 1, 'a')
sage: M = N.optimized_representation()[0]
sage: K = M.change_names(names='a')
sage: N == K
True
sage: N is K
False
sage: N.structure()
(Ring Coercion endomorphism of Number Field in a with defining polynomial
x^12 - 4*x^11 + 6*x^10 - 5*x^9 + 5*x^8 - 9*x^7 + 21*x^6 - 9*x^5 + 5*x^4 -
5*x^3 + 6*x^2 - 4*x + 1, Ring Coercion endomorphism of Number Field in a
with defining polynomial x^12 - 4*x^11 + 6*x^10 - 5*x^9 + 5*x^8 - 9*x^7 +
21*x^6 - 9*x^5 + 5*x^4 - 5*x^3 + 6*x^2 - 4*x + 1)
sage: K.structure()
(Isomorphism given by variable name change map:
From: Number Field in a with defining polynomial x^12 - 4*x^11 + 6*x^10
- 5*x^9 + 5*x^8 - 9*x^7 + 21*x^6 - 9*x^5 + 5*x^4 - 5*x^3 + 6*x^2 - 4*x + 1
To: Number Field in a6 with defining polynomial x^12 - 4*x^11 + 6*x^10
- 5*x^9 + 5*x^8 - 9*x^7 + 21*x^6 - 9*x^5 + 5*x^4 - 5*x^3 + 6*x^2 - 4*x +
1, Isomorphism given by variable name change map:
From: Number Field in a6 with defining polynomial x^12 - 4*x^11 + 6*x^10
- 5*x^9 + 5*x^8 - 9*x^7 + 21*x^6 - 9*x^5 + 5*x^4 - 5*x^3 + 6*x^2 - 4*x + 1
To: Number Field in a with defining polynomial x^12 - 4*x^11 + 6*x^10
- 5*x^9 + 5*x^8 - 9*x^7 + 21*x^6 - 9*x^5 + 5*x^4 - 5*x^3 + 6*x^2 - 4*x +
1)
}}}
Would it make sense to declare two number fields different if they have
different `structure()`?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11670#comment:13>
Sage <http://www.sagemath.org>
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