Note that all of the minterms covered by the essential prime implicants are checked, not just those columns with shaded X’s. The table is now reduced to that of Table 4.6 by eliminating the essential prime implicant rows and the covered minterms. In this simple example, the answer is apparent. Prime implicant H covers the remaining 1’s; any other solution would require at least two more terms, for a total of four. Thus, the solution is