Wally and his friends are hiding on this page, can you find them?

• Write following facts:
  1. is_left_of(X,Y) : X is directly left of Y
  2. is_below_of(X,Y) : X is directly below Y
• Write following predicates in terms of the previous predicates:
  1. is_right_of(X,Y) : X is directly right of Y
  2. is_above_of(X,Y) : X is directly above Y

Note that Wally is better at hiding in the books by Martin Handford.