#7797: Full interface to letterplace from singular
-------------------------------------------------------------------+--------
Reporter: burcin |
Owner: jdemeyer
Type: enhancement |
Status: needs_work
Priority: major |
Milestone: sage-5.4
Component: algebra |
Resolution:
Keywords: singular, free algebra, letterplace | Work
issues:
Report Upstream: None of the above - read trac for reasoning. |
Reviewers: Alexander Dreyer
Authors: Simon King, Michael Brickenstein, Burcin Erocal | Merged
in:
Dependencies: #4539, #11268, #12461, #12749, #12988, #13237 |
Stopgaps:
-------------------------------------------------------------------+--------
Comment (by SimonKing):
Replying to [comment:88 jdemeyer]:
> {{{
> sage -t
"devel/sage/sage/algebras/letterplace/free_algebra_letterplace.pyx"
> **********************************************************************
> File
"/home/jdemeyer/mark/sage-5.4.beta0/devel/sage/sage/algebras/letterplace/free_algebra_letterplace.pyx",
line 684:
> sage: G = F._reductor_(I.gens(),3); G
> Expected:
> Ideal (x*y_1 + y*z_1, x_1*y_2 + y_1*z_2, x*x_1 + x*y_1 - y*x_1 -
y*y_1, x_1*x_2 + x_1*y_2 - y_1*x_2 - y_1*y_2) of Multivariate Polynomial
Ring in x, y, z, x_1, y_1, z_1, x_2, y_2, z_2, x_3, y_3, z_3 over Rational
Field
> Got:
> Ideal (x*y_1 + y*z_1, x_1*y_2 + y_1*z_2, x*x_1 + x*y_1 - y*x_1 -
y*y_1, x_1*x_2 + x_1*y_2 - y_1*x_2 - y_1*y_2) of Multivariate Polynomial
Ring in x, y, z, x_1, y_1, z_1, x_2, y_2, z_2 over Rational Field
> **********************************************************************
> }}}
>
> This calls for some further investigation...
That test is about an internally used method (note the underscores), and
the output depends on a polynomial ring that is used to simulate
computations in free associative algebras out to a certain degree. As you
can see, the ideal we expect and the ideal we got are alike - only the
polynomial rings differ.
The point is that the underlying polynomial ring can change during
computations, and the free associative algebras are unique parents. Hence,
if tests are executed in different order then it may very well be that the
polynomial ring used behind the scenes is different. Only the final result
(i.e., interpreted in the free associative algebra) is unique.
I suggest to modify that test (and perhaps others as well) as follows:
{{{
> sage: G = F._reductor_(I.gens(),3); G
> Expected:
> Ideal (x*y_1 + y*z_1, x_1*y_2 + y_1*z_2, x*x_1 + x*y_1 - y*x_1 -
y*y_1, x_1*x_2 + x_1*y_2 - y_1*x_2 - y_1*y_2) of Multivariate Polynomial
Ring in x, y, z, x_1, y_1, z_1, x_2, y_2, z_2... over Rational Field
}}}
The variables before the `...` are guaranteed to occur, and we don't know
(and don't care) whether more variables appear behind the scenes.
Would you accept that solution?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7797#comment:89>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
