Lazy callback ignored bey the solver

[kianoush....@gmail.com]

Hi,

I'm applying benders cut to my problem, here is the part of the code that I apply the lazy constraint:

        if (status==GRB.INFEASIBLE):

                    print Pai

                    print Gamma

                    print Beta

                    cut=LinExpr()

                    cut=quicksum( (1-model._y[j])*Pai[j] for j in range(J))+ quicksum(Gamma[k] for k in range(K))+quicksum(model._w[i,j]*Beta[i,j,k] for i in range(I) for j in range(J) for k in range(K))>=0

                    print cut

                    model.cblazy( cut >=0)

I checked the cut linear expression and it seems fine but the solver gives me the error below:

Exception AttributeError: AttributeError("'gurobipy.Model' object has no attribute 'cblazy'",) in 'gurobipy.callbackstub' ignored

I also applied set these parameters as below:

self.MP.params.LazyConstraints = 1

        self.MP.params.Presolve = 0

        self.MP.Params.DualReductions =  0

Do you have any idea what elase could be the source of this error?

Thanks!

-Kianoush

[Silke Horn]

Hi Kianoush,

The method is called “cbLazy” (with an upper case L).

- Silke

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