#13758: Deprecate number field fractional ideal functionality that contradicts
standard Sage conventions
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Reporter: roed | Owner: davidloeffler
Type: defect | Status: new
Priority: major | Milestone: sage-5.6
Component: number fields | Keywords:
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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Sage does not currently support orders in number fields or their ideals.
Part of the reason for that is that all ideals are in fact just fractional
ideals.
{{{
sage: R.<x> = QQ[]
sage: K.<a> = NumberField(x^2 - 2)
sage: OK = K.maximal_order()
sage: I = K.ideal(3)
sage: I.ring() is K
True
sage: J = OK.ideal(3)
sage: J.ring() is OK
False
sage: I == J
True
}}}
I propose that `K.ideal(3)` should be replaced by `K.fractional_ideal(3)`,
that `I.ring()` and `J.ring()` should both return `OK`: the ring for which
this "ideal" is a module. To get the number field out of `I` or `J` use
the `number_field()` function instead.
Since making such a change suddenly is frowned upon, this ticket
deprecates the functions `ideal()` and `ring()` so that we can change
their meaning in a future version of Sage.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13758>
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