#12091: bug in add_constraint to MixedIntegerLinearProgram
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Reporter: dimpase | Owner: ncohen
Type: defect | Status: new
Priority: critical | Milestone: sage-4.8
Component: linear programming | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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constraints with 0 on one size of an inequality get lost, somehow:
{{{
sage: p = MixedIntegerLinearProgram(maximization=True)
sage: A = p.new_variable()
sage: p.add_constraint(A[0]==1)
sage: p.add_constraint(0<= A[1]-A[0])
sage: p.show()
Maximization:
Constraints:
1.0 <= x_0 <= 1.0
Variables:
x_0 is a continuous variable (min=0.0, max=+oo)
x_1 is a continuous variable (min=0.0, max=+oo)
}}}
homogenizing the constraint fixes this problem:
{{{
sage: p.add_constraint(0*A[0]<= A[1]-A[0])
sage: p.show()
Maximization:
Constraints:
1.0 <= x_0 <= 1.0
x_0 -x_1 <= 0.0
Variables:
x_0 is a continuous variable (min=0.0, max=+oo)
x_1 is a continuous variable (min=0.0, max=+oo)
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12091>
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