"Pattern-Based Constraint Satisfaction and Logic Puzzles (Second Edition)" develops a pure logic, pattern-based perspective of solving the finite Constraint Satisfaction Problem (CSP), with emphasis on finding the "simplest" solution. Different ways of reasoning with the constraints are formalised by various families of "resolution rules", each of them carrying its own notion of simplicity. A large part of the book illustrates the power of the approach by applying it to various popular logic puzzles. It provides a unified view of how to model and solve them, even though they involve very different types of constraints: obvious symmetric ones in Sudoku, non-symmetric but transitive ones in Futoshiki, topological and geometric ones in Map colouring, Numbrix and Hidato, non-binary arithmetic ones in Kakuro and both non-binary and non-local ones in Slitherlink. It also shows that the most familiar techniques for these puzzles can be understood as mere application-specific presentations of the general rules.

"The Hidden Logic of Sudoku" provides the first systematic perspective of the logical foundations and of the symmetries of the popular game. These are fully exploited to define new resolution rules, new graphical representations and an ordering of the rules consistent with their complexity. The classical pattern of xy-chains has been extended into a homogeneous set of chain rules that, when added to a few elementary rules, suffices to solve almost any puzzle. These rules are illustrated with a hundred puzzles with their full resolution paths. A large collection of puzzles has been processed by Artificial Intelligence (AI) techniques, leading to a precise evaluation of the efficiency of each rule. This pedagogical book is intended for both Sudoku players (who will discover many new facets of the game and new rules - all set in a uniform conceptual framework based on patterns) and teachers or students of Logic or AI (who will appreciate the strict logical foundations).