The Principle of Modularity
We propose a new principle of modularity for product design in cases where more than one function and more than one constraint contribute to modularity. The modularity matrix is defined as a set of permissible ranges for both functions and constraints. In introducing entropy from statistical mechanics, the concept of entropy highlights the number of possible options to realize the optimal value of a product. From the law of entropy maximization, we clarify the principle of modularity as the manner in which the matrix elements of modularity matrix should change in order to realize the highest value of products. We also propose that customer needs in the modularity matrix can be mapped to functional requirements through marketing activities with market uncertainty. From the analogy of econophysics, the principle of modularity is an extension of the utility theory in economics.