Friendlier IIS output

[datejada]

The current version detects the IIS, but the output is not that friendly to read:

## List of issues

 * Irreducible Infeasible Subset: MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.EqualTo{Float64}}(11), MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.EqualTo{Float64}}(12), MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.EqualTo{Float64}}(155), MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.EqualTo{Float64}}(156), MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.EqualTo{Float64}}(299), MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.EqualTo{Float64}}(300)

Is it possible to see it in a friendlier way?

The problem is the same as in: #32

Additionally, as a reference, the same issue includes an output from the IIS in a commercial solver.

Thanks!

[joaquimg]

Given this problem:

model = Model(HiGHS.Optimizer)
set_silent(model)
@variable(model, 0 <= x <= 10)
@variable(model, 0 <= y <= 20)
@variable(model, 0 <= z <= 20)
@constraint(model, c0, 2z <= 1)
@constraint(model, c00, 3z <= 1)
@constraint(model, c1, x + y <= 1)
@constraint(model, c2, x + y >= 2)
@objective(model, Max, x + y)
optimize!(model)
data = ModelAnalyzer.analyze(
    ModelAnalyzer.Infeasibility.Analyzer(),
    model,
    optimizer = HiGHS.Optimizer,
)

You can run:
ModelAnalyzer.summarize(data, model = model)
That will give you something like:

## List of issues

 * Irreducible Infeasible Subset: c2, c1

instead of:

## List of issues

 * Irreducible Infeasible Subset: MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.GreaterThan{Float64}}(1), MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.LessThan{Float64}}(3)