Page 124

Location: Chapter 12, Exercise 5(a) at end of chapter

It is (requirement on the bird)

\[ \Gamma xyzwv = y(zw)(xywv) \]

It should become

\[ \Gamma xyzwv = y(zw)(xyzwv) \]

Short explanation

The need for the missing variable in the definition can be confirmed by plugging in the solution for \(\Gamma\) given a few pages later.