Methods and systems are provided to reduce the complexity of sequential digital circuitry including cells of unknown function by grouping and defining like instance of combinational circuitry cells. The system groups together cells that feed into the same combination of one or more state cells. The groups of cells are then replaced by clouds which are defined in the netlist for the sequential digital circuitry to produce a simpler representation of the circuitry for analysis purposes and to aid in determining the function of those cells for which the function is unknown.