On a mixed integer linear program, LINGO can perform an operation known as probing. Probing involves taking a close look at the integer variables in a model and deducing tighter variable bounds and righthand side values. In many cases, probing can tighten an integer model sufficiently, and, thereby, speed overall solution times. In other cases, however, probing may not be able to do much tightening, and the overall solution time will increase due to the extra time spent probing. You can choose from seven successive levels of probing ranging from 1 to 7. Level 1 disables probing completely, while level 7 involves the highest degree of probing. Setting this option to 0 lets LINGO select the level of probing. LINGO defaults to 0.