Learning With Perfect Domain Theories

A perfect domain theory is correct and complete.
A domain theory is correct if each of its assertions is a truthful statement about the world.
A domain the is complete wrt target concept and X, if it covers every positive example in the instance space.
So, if we have a perfect domain theory, why do we need to learn?
Chess. Often the theory leads to too many deductions (large breadth) making it impossible to find the optimal strategy. The examples help to focus search.
Perfect domain theories are often unrealistic, but, learning in them is a first step before learning with imperfect theories (next chapter).
Prolog-EBG is an EBL learner. It uses sequential covering.