"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 formulæ 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.