Constant term

[DemeulemeesterT]

Is there a reason why the constant term is not included in the .lp file that is generated by pulp?

In the Gurobi output, this constant term is also not included. But when calling for the optimal objective value afterwards, it is again included. It took me a while to figure this out.

Below is a minimal example that illustrates this:

[pchtsp]

Because a constant term in an objective function is irrelevant for MIP solvers. You can always add the constant value after solving the problem.

[DemeulemeesterT]

Of course, but sometimes the exact objective value matters (think about the pricing problem in a column generation framework, for example).

Anyhow, now I know in which parts the constant term is and isn't included ;)