#12547: Single variable inequalities in MixedIntegerLinearProgram should set the
min and max automatically
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Reporter: ppurka | Owner: ncohen
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: linear programming | Keywords: MixedIntegerLinearProgram
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies: 12546
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Comment(by ncohen):
Hellooooooooooo !!
This problem has already been reported in #12091. Besides, there is *no
reason on earth why Sage should change lower bounds because of
constraints*. This would be *VERY* bad. I mean, which kind of behaviour is
that ? If you add two constraints, one loser than the first, the solver
should only remember the losest one ? Or only when it is "one variable"
and "its lower bound" ?
The thing about constraints is that they are generated from a specific
problem. If for some unknown reason the constraints generated are of the
form "b[i] >= -2" the LP would now let b[i] have negative values, and
that's just NOT what was intended.
Plus it's not really like this is some specificity of Sage. ALL (no
exceptions) LP solvers work this way.
Nathann
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12547#comment:1>
Sage <http://www.sagemath.org>
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