Beat Bruderlin & Dieter Roller 
Geometric Constraint Solving and Applications [PDF ebook] 

Geometric constraint programming increases flexibility in CAD design specifications and leads to new conceptual design paradigms.This volume features a collection of work by leading researchers developing the various aspects of constraint-based product modeling.In an introductory chapter the role of constraints in CAD systems of the future and their implications for the STEP data exchange format are discussed. The main part of the book deals with the application of constraints to conceptual and collaborative design, as well as state-of-the-art mathematical and algorithmic methods for constraint solving.