Context: All customer pairs (C1,C2) such that C1 likes some pizza that C2 does not like.
LikeDislike(cname, cname2):
Question: Find all customer pairs (C1,C2) such that C1 < C2 and they like exactly the same pizzas.
Answer:
I'm not sure about the right side of the operator tree. Why does the answer include LikeDislike? When they are asking about C1 & C2 liking exactly the same pizzas.