
speak of optimal, solutions. What is needed to make design practical are powerful
strategies that radically shrink the search space.
2.2 What Kind of Space to Search?
The idea of search in a state space goes back to the early days of Al, and Newell
[Newell 80] has formalized the Problem Space Hypothesis essentially stating that all
goal-directed behavior takes place in some problem space.
Before search can take place, the problem space needs to be defined. But design
problem-solving does not have a unique problem space. Different kinds of problem
spaces can be visualized, each appropriate for some kinds of domain knowledge and
not others. Fo ...