#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 ppurka):
I think mixed chained inequalities/equalities could be errored out. That
would ensure that such obtuse inputs are taken care of.
The reason for providing chained inequalities is to actually give
inequalities in the form {{{2 <= x[0] <= 3}}} or {{{2 >= x[1] >= 1}}},
instead of having to set them separately. These types of inequalities are
quite common to encounter, and it helps the user if the mathematical
expressions can be transferred to sage in a straightforward manner.
Examples like {{{x[0] <= x[1] >= x[2]}}} or {{{x[0] <= x[1] == 2}}} are
quite unusual. I have never seen such expressions come up naturally. The
first example, for instance, says nothing about the relation between
`x[0]` and `x[2]` and hence one would typically never encounter
inequations (written) like that.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12091#comment:30>
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