Representation of Multivalued Functions Using the Direct Cover Method

An efficient method for representing multivalued functions is described. The method employs an algorithm which generates an efficient cover for a given function "directly," i.e., without resorting to the intermediate step of creating a table of prime implicants. Data are presented to show that the covers generated are as efficient in terms of cover size as prime implicant based methods. More importantly, however, the direct cover method is shown to require much less computation time than prime implicant based methods, thus making it practical for functions with a large number of input variables and/or as the radix of implementation increases. The algorithm is introduced by applying it to functional representations employing the traditional max and min operation. Next, a modified form of the algorithm is presented for use with the sum and product operators more appropriate to I2L and other current summation technologies.