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Irreducible Infeasible Sets Description Shows how to analyze an infeasible problem by retrieving an irreducible infeasible subset Further explanation of this example: 'Xpress Python Reference Manual'
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example_infeasible.py
# Example that shows how to treat an infeasible problem.
#
# (C) Fair Isaac Corp., 1983-2024
from __future__ import print_function
import xpress as xp
minf = xp.problem("ex-infeas")
x0 = minf.addVariable()
x1 = minf.addVariable()
x2 = minf.addVariable(vartype=xp.binary)
c1 = x0 + 2 * x1 >= 1
c2 = 2 * x0 + x1 >= 1
c3 = x0 + x1 <= .5
minf.addConstraint(c1, c2, c3)
minf.optimize()
minf.iisall()
print("there are ", minf.attributes.numiis, " iis's")
miisrow = []
miiscol = []
constrainttype = []
colbndtype = []
duals = []
rdcs = []
isolationrows = []
isolationcols = []
# get data for the first IIS
minf.getiisdata(1, miisrow, miiscol, constrainttype, colbndtype,
duals, rdcs, isolationrows, isolationcols)
print("iis data:", miisrow, miiscol, constrainttype, colbndtype,
duals, rdcs, isolationrows, isolationcols)
# Another way to check IIS isolations
print("iis isolations:", minf.iisisolations(1))
rowsizes = []
colsizes = []
suminfeas = []
numinfeas = []
print("iisstatus:", minf.iisstatus(rowsizes, colsizes, suminfeas, numinfeas))
print("vectors:", rowsizes, colsizes, suminfeas, numinfeas)
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| © Copyright 2024 Fair Isaac Corporation. |
