Chapter 17 Conditional Probability738
(d)What is the probability that two distinct verticesxandy lie on a three-
cycle inG? Answer with a simple expression in terms ofpandr, whererWWD
PrŒNOT.P.x;y//çis the correct answer to part (c).
Hint:Expressxandybeing on a three-cycle as a simple formula involvingE.x;y/
andP.x;y/.