A Rational Model of the design process
UNTIL (“good enough”) or (time runs out)
DO another design (to improve utility function)
UNTIL design is complete
WHILE design remains feasible,
make another design decision
Backtrack up design tree
Explore a path not searched before
Take best design
... [F]or the theory of design is that general theory of search ... through large combinatorial spaces.
HERBERT SIMON , THE SCIENCESOF THE ARTIFICIAL, 54
Engineers seem to have a clear, if usually implicit, model of the process of design. ...