This function returns a constraint that states that whenever interval variable a is present, it cannot start at a value t when f(t)=0. You must add this constraint to a model and extract the model to an algorithm in order for it to be taken into account.

This constraint is often used in combination with an intensity function to state that the interval variable cannot start at a point where its intensity function is zero.

Note: This constraint cannot be used in a logical constraint.

For more information on forbidden placements of interval variables, see the concept Intensity and size and forbidden values.