## The Hidden Logic of Sudoku
## Denis Berthier
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(First edition published by Lulu.com, May 2007, ISBN : 978-1-84753-472-9) |

© Denis Berthier. All the material in this page and the pages it gives access to are the property of the author and may not be re-published or re-posted without his prior written permission. |

In addition to a few elementary rules, the very classical and basic pattern of xy-chains has been extended, as far as its underlying logic allowed, to a homogeneous set of chain rules of progressively increasing complexity. It suffices to solve almost any puzzle without making guesses, without dealing with chains of subsets or with nets and without assuming the uniqueness of a solution. These rules are illustrated with a hundred puzzles, together with their full resolution paths. They have been tested in an Artificial Intelligence (AI) engine and tens of thousands of puzzles have been processed, leading to a precise evaluation of the efficiency of each rule. This book is intended for Sudoku players of all levels: they will discover many new facets of the game and new types of resolution rules - introduced in a pedagogical way and set in a uniform conceptual framework based on patterns. It is also intended for teachers or students of Logic or AI: they will appreciate the strict logical foundations.
What's new in the second edition (pdf) |

## ONLINE SUPPLEMENTS TO THE BOOK## for advanced players (not the good place to start with) |