MathOptIIS.jl

MathOptIIS.jl is a basic IIS solver for MathOptInterface.jl.

License

MathOptIIS.jl is licensed under the MIT License.

Getting help

If you need help, please ask a question on the JuMP community forum.

If you have a reproducible example of a bug, please open a GitHub issue.

Installation

Install MathOptIIS using Pkg.add:

import PkgPkg.add("MathOptIIS")

Usage

MathOptIIS is not intended to be called directly from user-code. Instead, it should be added as a dependency to solver wrappers that want to provide an IIS.

To add to an existing wrapper, add a new field:

conflict_solver::Union{Nothing,MathOptIIS.Optimizer}

Then, add the following methods:

function MOI.compute_conflict!(model::Optimizer)    solver = MathOptIIS.Optimizer()    MOI.set(solver, MathOptIIS.InfeasibleModel(), model)    MOI.set(solver, MathOptIIS.InnerOptimizer(), Optimizer)    # Optional: set the solver's silent to true or false. In this example,    # follow the outer attribute.    MOI.set(solver, MOI.Silent(), MOI.get(model, MOI.Silent()))    # Optional: set a time limit. In this case, 60 seconds.    MOI.set(solver, MOI.TimeLimitSec(), 60.0)    MOI.compute_conflict!(solver)    model.conflict_solver = solver    returnendfunction MOI.get(optimizer::Optimizer, attr::MOI.ConflictStatus)    if optimizer.conflict_solver === nothing        return MOI.COMPUTE_CONFLICT_NOT_CALLED    end    return MOI.get(optimizer.conflict_solver, attr)endfunction MOI.get(optimizer::Optimizer, attr::MOI.ConflictCount)    if optimizer.conflict_solver === nothing        return 0    end    return MOI.get(optimizer.conflict_solver, attr)endfunction MOI.get(    optimizer::Optimizer,    attr::MOI.ConstraintConflictStatus,    con::MOI.ConstraintIndex,)    return MOI.get(optimizer.conflict_solver, attr, con)end

The name

The optimization community consistently uses "IIS", but they have not standardized on what the acronym stands for. We have seen:

1. Irreducible Infeasible Set
2. Irreducibly Inconsistent Set
3. Irreducible Infeasible Subsystem
4. Infeasible Irreducible System
5. Irreducible Inconsistent Subsystem
6. Irreducibly Inconsistent System

So we choose the name MathOptIIS, and you can decide what the acronym stands for.