Lulu Press, 2012 - 2nd edition - 53 pages - 6" x 9" format - public domain code
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This small book answers all these questions in about 50 pages of prose.
Chapter 1 introduces basic logic programming techniques.
Chapter 2 applies the techniques to a well-known puzzle. (No, not the one on the cover page.)
Chapter 3 rolls your own logic programming system in 170 lines of Scheme.
The code in this book is purely functional, purely symbolic, and easy to follow.