To ensure no two specific objects are adjacent: first arrange the remaining objects, then place restricted objects in the gaps. For example, arrange 5 boys in a row (5! ways), creating 6 gaps (_B_B_B_B_B_). Place 3 girls in these 6 gaps: P(6,3) = 120. Total = 5! * 120 = 14400. This is more efficient than complementary counting when the number of restricted objects is small.