1. A computer-implemented method of producing a verification report of a digital design comprising: generating a description of a digital design; generating a set of Boolean constraints and a set of integer constraints describing a valid set of input stimuli for the design description, including: randomly selecting a Boolean or an Integer sample variable; randomly changing the state of the selected sample variable; and determining a change in the number of satisfied clauses in combined set of Boolean and Integer constraints; generating a mixed Boolean-Integer input stimuli set for the digital design description, the input stimuli satisfying the set of Boolean constraints and the set of integer constraints; performing, on a computing apparatus, a verification on the design description utilizing the input stimuli; and producing a verification report from the verification.