Findmiis

findMIIS(LPProblem, printLevel)

Finds the Minimal Irreducible Infeasible Subset (MIIS) in an infeasible linear program. It uses (for now) the IBM ILOG CPLEX conflict refine routine. The MIIS is the smallest infeasible submodel that becomes feasible if one constraint/bound is removed. All subsets of a MIIS are feasible. Where relaxedFBA and feasOpt take corrective measures automatically, findMIIS points the user to the infeasible subset which guides decision making. The user can then check errors in the data or correct the model based on the literature.

USAGE:

MIIS = findMIIS (LPProblem, printLevel)

INPUTS:

• LPProblem – infeasible LP problem as a COBRA model/LP structure with fields:

  • .A - m x n constraint matrix (.S is used if .A is absent)

  • .S - m x n stoichiometric matrix (alternative to .A)

  • .b - m x 1 right-hand-side vector

  • .c - n x 1 linear objective coefficient vector

  • .lb - n x 1 lower bounds

  • .ub - n x 1 upper bounds

  • .csense - m x 1 constraint sense (‘E’, ‘G’, or ‘L’; default all ‘E’)

  • .osense - objective sense (-1 maximise, 1 minimise; default -1)

• printLevel – verbosity level, 0/1/2 (default 0)

OUTPUT:

MIIS –

structure describing the MIIS with fields:

• .rxns - reactions of the MIIS

• .mets - metabolites of the MIIS

• .rxnsStat - status of infeasibility of reactions

• .metsStat - status of infeasibility of metabolites

Refer to the IBM CPLEX solution status codes documentation for the meaning of the status values.