Predicate Calculus as Programming Language

1. New knowledge or methods can be added.

   Advantage: In theory, at least, the program can immediately combine new knowledge with existing knowledge.

   Disadvantage: The ``new knowledge'' may contradict or subsume existing knowledge without our being aware of it.

2. Predicate Calculus is completely ``unstructured''. Any two clauses which are unifiable may interact.
3. In order to make a program run in a reasonable length of time, it is usually necessary to restructure clauses to:
   • Order the search so the desired solution will be found rapidly.
   • Reduce the branching factor of the search tree.