Pattern-Oriented Analysis and Design (POAD) Theory
  Pattern-Oriented Analysis and Design (POAD) is the practice of building complex software by applying proven designs to specific problem domains. Although a great deal of research and practice has been devoted to formalizing existing design patterns and discovering new ones, there has been relatively little research into methods for combining these patterns into software applications. This is partly because the creation of complex software applications is so expensive. This paper proposes a mathematical model of POAD that may allow future research in pattern-oriented techniques to be performed using less expensive formal techniques rather than expensive, complex software development. 
Jerry Overton