Dr. Frank Rubin is a retired IBM® computer programmer who has done extensive work in the field of design automation, using computers to design the next generation of larger and faster computers. Dr. Rubin is also a cryptographer who holds major patents in the field of keyless cryptography. Beyond his professional activities, he has constructed thousands of mathematical puzzles, as well as cryptograms, alphametics, SumSum, Double Sudoku, and papers on knight and bishop coverings in chess. This is his first book for Puzzlewright Press.