#19538: Fix LaurentPolynomialRing coercion issues
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Reporter: | Owner:
etn40ff | Status: needs_review
Type: | Milestone: sage-6.10
defect | Resolution:
Priority: major | Merged in:
Component: | Reviewers:
algebra | Work issues:
Keywords: | Commit:
Authors: | 76ac4339b195762106d406516400f8468de844ef
Salvatore Stella | Stopgaps:
Report Upstream: N/A |
Branch: |
u/etn40ff/19358 |
Dependencies: |
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Comment (by vdelecroix):
Replying to [comment:10 etn40ff]:
> I am not really happy about the formulation of rule 2. What I mean by
this is
> that I find this example extremely confusing because it maps {{{y}}} to
{{{x}}}
> and {{{t}}} to {{{y}}}
>
> {{{
> sage: R1 = PolynomialRing(ZZ, 'x,y')
> sage: R5 = PolynomialRing(ZZ, 'y,t')
> sage: map(R1, R5.gens()) # rule 2
> [x, y]
> }}}
>
> What is the rationale behind it?
I would say: "A map between two rings is always better than a partial
map". Whatever you think it is how it works in Sage. If you want to change
it you should ask more opinions on
[https://groups.google.com/forum/#!forum/sage-devel sage-devel].
One possibility would be to modify the rule 2 in the following form
2'. else if `R` has less or equal variables than `S` then the map `R ->
S` is given by a mapping of the variables of `R` into `S` first trying to
match names and then in variable order.
But as I said, the place to discuss it is sage-devel and not a ticket.
--
Ticket URL: <http://trac.sagemath.org/ticket/19538#comment:11>
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