String-rewriting grammars for evolutionary architectural design

Evolutionary methods afford a productive and creative alternative design workflow. Crucial to success is the choice of formal representation of the problem. String-rewriting context-free grammars (CFGs) are one common option in evolutionary computation, but their suitability for design is not obvious. Here, a CFG-based evolutionary algorithm for design is presented. The process of meta-design is described, in which the CFG is created and then refined to produce an improved design language. CFGs are contrasted with another grammatical formalism better known in architectural design: Stiny's shape grammars. The advantages and disadvantages of the two types of grammars for design tasks are discussed. Keywords: evolutionary design, grammatical evolution, design languages, context-free grammar, shape grammar