Figure 4-15(a) shows the K map for a four-variable problem. We will assume that Step 1 (construct a K map from the problem truth table) has been completed.

The squares are numbered for convenience in identifying each loop. Use steps 2–7 of the simplification process to reduce the K map to an SOP expression.

Figure 4-15(a)

1222 AB AB CD AB 0 0 AB 0 0 5 9 13 CD 0 1 1 0 2 10 14 CD 0 1 1 1 7 11 15 CD 1. 0 0 0 12 16 X = ABCD (a) loop 4 + ACD loop 11, 15 + BD loop 6, 7, 10, 11