Discrete Optimisers - 09 - Even Better than Optimum?

You can’t get better than optimum. Or can you? The discrete optimisers are looking for the best possible solution for the traffic control system of the shipping on the Kiel Canal to minimise the length of time the ships have to wait. But how do they know when to stop looking because they have already found the best possible solution? Is there a way of proving an ideal solution mathematically? "Lower bounds" and "integer programming" can help...