Tricotyledon theory of system design

In systems engineering, the tricotyledon theory of system design (T3SD) is a mathematical theory of system design developed by A. Wayne Wymore. T3SD consists of a language for describing systems and requirements, which is based on set theory, a mathematical systems model based on port automata, and a precise definition of the different types of system requirements and relationships between requirements.

System requirements model

 * I/O requirement
 * Performance requirement
 * System test requirement
 * Cost requirement
 * Tradeoff requirement

System design

 * Based on set theory
 * Transition systems
 * Functional system design
 * Buildable system design