5.5 THE SOP-TO-EXSOP REED–MULLER TRANSFORMATION 207
easily obtained from that of Fig. 5.3a by introducing the coordinate values for X and Y into
Fig. 5.3b to obtain the subfunctions in terms of W and Z.
For complex functions involving five or more variables, the process of generating a
gate-minimum result by using XOR EV patterns becomes increasingly more a matter of
trial and error as the number of variables increases. Again, the application of the EV XOR
pattern approach to design is left more to the natural occurrence of such patterns than
it is to the hunt-and-choose method. However, if it is known that XOR patterns occur
naturally in some functions and if one is familiar with conventional (1’s and 0’s) K-map
methods for five or more variables,