CDG - Coverage Directed Generation
Modern verification uses random-coverage methodology. Random stimuli generators are used to produce a large number of test-cases, and coverage is used as the main metric, giving the verification team feedback on whether all interesting scenarios were exercised.
The analysis of coverage holes is a continuous manual process. It requires expert knowledge in the design under test, the verification environment, and the meaning of the directives given to the test generator.
The goal of the CDG engine is to provide, for a given coverage event or set of events, a setting of directives to the test generator that maximize (or at least significantly increase) the probability of hitting the given events.