Infeasible Irreducible System (IIS) Tool

This module contains functions for computing an irreducible infeasible set for a Pyomo MILP or LP using a specified commercial solver, one of CPLEX, Gurobi, or Xpress.

pyomo.contrib.iis.write_iis(pyomo_model, iis_file_name, solver=None, logger=<Logger pyomo.contrib.iis (INFO)>)[source]

Write an irreducible infeasible set for a Pyomo MILP or LP using the specified commercial solver.

Parameters:

  • pyomo_model – A Pyomo Block or ConcreteModel

  • iis_file_name (str) – A file name to write the IIS to, e.g., infeasible_model.ilp

  • solver (str) – Specify the solver to use, one of “cplex”, “gurobi”, or “xpress”. If None, the tool will use the first solver available.

  • logger (logging.Logger) – A logger for messages. Uses pyomo.contrib.iis logger by default.

Returns:

iis_file_name – The file containing the IIS.

Return type:

str