Non-Essential vs. Essential Prime Implicants
EACH of the coverings is a PRIME IMPLICANT.
F(A,B,C,D) = BC’ + A’B’D (minimum # of PIs)
Prime Implicant A’C’D is a NON-ESSENTIAL prime implicant because its ‘1’s are covered by other PIs . A PI is ESSENTIAL if it covers a MINTERM that cannot be covered by any other PI.