What are user cuts and lazy constraints?

Defines user cuts; defines lazy constraints.

In contrast to the cuts that IBM ILOG CPLEX may automatically add while solving a problem, user cuts are those cuts that a user defines based on information already implied about the problem by the constraints; user cuts may not be strictly necessary to the problem, but they tighten the model. Lazy constraints are constraints that the user knows are unlikely to be violated, and in consequence, the user wants them applied lazily, that is, only as necessary or not before needed. User cuts can be grouped together in a pool of user cuts. Likewise, lazy constraints can also be grouped into a pool of lazy constraints.