"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.

"Pattern-Based Constraint Satisfaction and Logic Puzzles" 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 (inequalities) in Futoshiki, topological and geometric ones in Map colouring, Numbrix and Hidato, and even much more complex non-binary arithmetic ones in Kakuro. It also shows that the most familiar techniques for these puzzles can indeed be understood as mere application-specific presentations of the general rules.

"Constraint Resolution Theories" introduces a pure logic perspective of the finite Constraint Satisfaction Problem (CSP), with emphasis on finding the "simplest" solution. Based on constructive logic, the resolution paradigm involves resolution rules, i.e. logical formulae in the condition-action form, where the condition pattern implies the elimination of a candidate (a possible value for a CSP variable). Defining a resolution theory as a set of resolution rules, it introduces several families of such theories. Each of them carries its own notion of simplicity, defines a rating of CSP instances and satisfies two main theorems: the confluence property (guaranteeing that the associated rating has good computational properties) and a correspondence with a form of structured search procedure without guessing (Trial-and-Error). Throughout the book, Sudoku is used for illustrative purposes.

"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).

The "Hidden Logic of Sudoku" provides the first systematic perspective of the logical symmetries of the popular game. These are fully exploited to define new graphical representations, new kinds of resolution rules and a precedence ordering of the rules consistent with their logical complexity. The set of rules defined in the book is illustrated with a hundred of puzzles together with their full resolution paths. It suffices to solve almost any puzzle without making guesses or assuming the uniqueness of a solution. It has been fed into an Artificial Intelligence (AI) engine and a large database of puzzles has been processed, leading to a precise evaluation of the efficiency of each rule. The book is intended for both advanced Sudoku players (who will discover many new facets of the game and a new, systematic approach to the resolution rules) and for teachers or students of Logic or AI (who will appreciate the strict logical foundations).

Denis Berthier has spent thirty years observing the night sky from within a city and his practical guide will enable amateur astronomers to observe and photograph stars, planets and other celestial objects from their own town. It is becoming more and more difficult to find an observing site with clear, dark skies away from light and industrial pollution. However, by choosing the right targets to observe, with patience and simple equipment, amateur astronomers can still find observing from towns and cities to be a rewarding hobby. Denis Berthier is the French journalist who has been passionate about astronomy for the last thirty years. He has been Laureate of the French Association for Astronomy and has published numerous papers on astronomical photography and instrument construction.