#7580: bugs in infinite polynomial ring
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Reporter: was | Owner: SimonKing
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.3.1
Component: algebra | Keywords: infinite polynomial ring coercion
Work_issues: | Author: Simon King
Upstream: N/A | Reviewer:
Merged: |
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Comment(by SimonKing):
Hi John!
Replying to [comment:22 cremona]:
> I don't want to join in the reviewing of this in any serious way since
I'm a late arrival to the scene,
Welcome! You are not late at all, I think...
> but I have one minor request: the is_proof() function for infinite
polynomial rings returns False always -- fine, but the functions needs to
have a (redundant) proof parameter since it is overriding a similar
function in a base class.
I am not sure I understand what you mean. There are two "is_*" methods
that I overwrote: is_noetherian and is_field. In the first case, no
optional parameters are accepted. Should they be? Anyway, since infinite
polynomial rings aren't noetherian rings, False is always the right answer
(although they are noetherian modules over the group ring of the infinite
symmetric group).
In the second case, keyword arguments are accepted, but ignored (since an
infinite polynomial rings can never be a field, False is returned).
> I came across this in trying something out which involved constructing a
univariate polynomial ring over an infinite poly ring, and some function
wanted to know if the base ring for that was a field, so called is_field()
like this:
> {{{
> elif base_ring.is_field(proof = False):
> }}}
> (line 422 of sage/rings/polynomial/polynomial_ring_constructor.pyc)
which caused a run time error. Thanks!
Can you give me an example? The following works fine:
{{{
sage: IP.<x,y> = InfinitePolynomialRing(QQ)
sage: R.<a> = IP[]
sage: R.base_ring().is_field(proof=False)
False
}}}
Cheers,
Simon
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7580#comment:23>
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