#12091: chained inequalities bug in add_constraint to MixedIntegerLinearProgram
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Reporter: dimpase | Owner: ncohen
Type: defect | Status: new
Priority: major | Milestone: sage-5.4
Component: linear programming | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by dimpase):
Replying to [comment:28 vbraun]:
> I agree that it is odd behavior. The whole idea of automatically
converting all inequalities into less-or-equal is broken, even before my
patch:
> {{{
> sage: (b[0] <= b[1]) >= b[2]
> x_2 <= x_0 <= x_1
> }}}
> Inequalities need to remember `>=` vs. `<=` for us to be able to raise
an error.
Anything wrong with having that much more in the inequalities class?
Potentially one would also want to have {{{<}}} and {{{>}}} and a proper
integration with Sage's polyhedra.
Your patch also inspires a grand plan for
[http://en.wikipedia.org/wiki/Linear_matrix_inequality linear matrix
inequalities] in Sage...
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12091#comment:29>
Sage <http://www.sagemath.org>
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