 A charming foray into combinatory logic is presented in Smullyan 1985 and Glickfeld &amp; Overbeek 1986, where we learn about a certain enchanted forest inhabited by talking birds. Given any birds A and B, if the name of bird B is spoken to bird A then A will respond with the name of some bird in the forest, AB, and this response to B from A will always be the same. Here are some definitions about enchanted birds: 