# KY Birds…which book is that from.

I am trying to find the name of this mathematical book, a smart student at my university gave a lecture about it a long time ago, and all I can remember of the talk was

• it was about mathematics
• it had birds
• one of the birds had the name KY.

I have tried google to find the title or author; however, searching with KY doesn't result in any thing mathematical.

I am asking here because someone here should know the Title of the book.

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I have no idea what you could possibly mean by either "birds" or "KY" in a mathematical context. Closed. – Qiaochu Yuan Jan 26 '12 at 20:08
@qiaochu yuan The book used the example of birds and one type of the birds was KY...I think it had something to do with algebra. – yiyi Jan 26 '12 at 20:10
To Mock a Mockingbird and Other Logic Puzzles: Including an Amazing Adventure in Combinatory Logic by Raymond Smullyan – aaa Jan 26 '12 at 20:28
@QiaochuYuan The book name is "To Mock a Mockingbird and Other Logic Puzzles: Including an Amazing Adventure in Combinatory Logic" by Raymond Smullyan. I wasn't being vulgar and yes I have tried searching for the book with the information I remembered from the talk. – yiyi Jan 26 '12 at 21:12
@aaa: You should post that as an answer (when the question is reopened). Frankly though, if I hadn't been told about it a few weeks ago I would never have guessed the question had anything to do with combinatory logic. – Zhen Lin Jan 28 '12 at 17:59

## 1 Answer

The book name is "To Mock a Mockingbird and Other Logic Puzzles: Including an Amazing Adventure in Combinatory Logic" by Raymond Smullyan.

A certain enchanted forest is inhabited by talking birds. Given any birds A and B, if you call out the name of B to A, then A will respond by calling out the name of some bird to you; this bird we designate AB. Thus AB is the bird named by A upon hearing the name of B.

In the beginning, there is about hundred pages with unrelated logic puzzles and the rest of the book (about 200 pages) is about a policeman exploring different forests populated with different combinatory logic birds.

For example, Mockingbird is a combinator M defined

M x = x x


Bluebird is

B x y z = x (y z)


and so on ;-)

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Just a note, that this is not as obscure terminology as it seems. There is a self published e-book that uses it. combinators.info It mostly deals with trying to bring the concepts to programming in Ruby. – user7610 Jul 20 '13 at 22:25
There is even a scientific paper that can be found through scholar.google.com that uses this terminology. – user7610 Mar 20 '14 at 17:25