problem.getiisdata

Purpose

Returns information for an Irreducible Infeasible Set: size, variables (row and column vectors) and conflicting sides of the variables, duals and reduced costs.

Synopsis

problem.getiisdata(num, miisrow, miiscol, constrainttype, colbndtype, duals, rdcs, isolationrows, isolationcols)

Arguments

num

The ordinal number of the IIS to get data for.

miisrow

Indices of rows in the IIS. Can be None if not required.

miiscol

Indices of bounds (columns) in the IIS. Can be None if not required.

constrainttype

Sense of rows in the IIS:

L	for less or equal row;
G	for greater or equal row.
E	for an equality row (for a non LP IIS);
1	for a SOS1 row;
2	for a SOS2 row;
I	for an indicator row.

Can be None if not required.

colbndtype

Sense of bound in the IIS:

U	for upper bound;
L	for lower bound.
F	for fixed columns (for a non LP IIS);
B	for a binary column;
I	for an integer column;
P	for a partial integer columns;
S	for a semi-continuous column;
R	for a semi-continuous integer column.

Can be None if not required.

duals

The >dual multipliers associated with the rows. Can be None if not required.

rdcs

The dual multipliers (reduced costs) associated with the bounds. Can be None if not required.

isolationrows

The isolation status of the rows:

-1	if isolation information is not available for row (run iis isolations);
0	if row is not in isolation;
1	if row is in isolation.

Can be None if not required.

isolationcols

The isolation status of the bounds:

-1	if isolation information is not available for column (run iisisolations);
0	if column is not in isolation;
1	if column is in isolation. Can be None if not required.

Example

This example first retrieves the size of IIS 1, then gets the detailed information for the IIS.

miisrow = []
miiscol = []
constrainttype = []
colbndtype = []
duals = []
rdcs = []
isolationrows = []
isolationcols = []
p.getiisdata(1, miisrow, miiscol, constrainttype, colbndtype,
              duals, rdcs, isolationrows, isolationcols)

Further information

1. IISs are numbered from 1 to NUMIIS. Index number 0 refers to the IIS approximation.

2. If miisrow and miiscol both are None, only the rownumber and colnumber are returned.

3. The arrays may be None if not required. However, arrays constrainttype, duals and isolationrows are only returned if miisrow is not None. Similarly, arrays colbndtype, rdcs and isolationcols are only returned if miiscol is not None.

4. For the initial IIS approximation ( num = 0) the number of rows and columns with a nonzero Lagrange multiplier (dual/reduced cost respectively) are returned. Please note that in such cases, it might be necessary to call problem.iisstatus to retrieve the necessary size of the return arrays.

5. If there are Special Ordered Sets in the IIS, their number is included in the miisrow array.

6. For non-LP IISs, some column indices may appear more than once in the miiscol array, for example an integrality and a bound restriction for the same column.

7. Duals, reduced cost and isolation information is not available for nonlinear IIS problems, and for those the arrays are filled with zero values in case they are provided.

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problem.getiisdata

problem.getiisdata