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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 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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