Much of AI research is about problem-solving strategies, andseveral techniques have been crystalized. One such techniqueis constraint satisfaction or reasoning based on relations.Constraint-based reasoning is used to solve a wide field ofproblems, and recently constraint techniques have beenincorporated into logic programming languages, yielding awhole new field of research and application: constraintlogic programming. Constraint satisfaction techniques havebecome part of almost all introductory books on AI.This monograph is about constraint satisfaction. It differsfrom others in that it presents all approaches under acommon, generalizing view: dynamic constraints. This new wayof viewing constraints provides new insights about thedifferent approaches, and forms a very practical basis forteaching constraint-based reasoning. A uniform view of theconstraint world is also a good basis for constraintresearch. This text is not intended to be a self-containedtextbook on constraint-based reasoning, but rather acoherent text on an interesting view of the field.