apparatus for presentation of functional coverage , including one or more processors and a memory , wherein the memory stores software instructions including instructions for representing a set of attributes of a design under test as a multi - dimensional cross - product space , comprising events corresponding to combinations of values of the attributes to be tested , the events comprising legal and illegal events , instructions for running at least one test on the design , instructions for identifying , responsively to the at least one test , a first group of the legal events that were covered by the at least one test and a second group of the legal events that remain non - covered after the at least one test , instructions for grouping one or more of the illegal events with at least one of the first and second groups so as to generate a simplified model of the functional coverage of the events in the cross - product space and instructions for presenting the simplified model of the functional coverage on an output device . the apparatus further includes an output device coupled to the coverage processor to present the simplified model of the functional coverage to a user .