From Cases to Rules

Inductive reasoning aims at finding general rules that hold true in the database. Such rules may state that a certain phenomenon never happens, that certain conditions necessitate another, or that one variable is a function of others. We show that several problems associated with these processes are computational hard. In particular, in the context of linear regression, finding a small set of variables that obtain a certain value of R2 is computationally hard. Computational complexity may explain why a person is not always aware of rules that, if asked, she would find valid. This may explain why one can often change other people�s minds (opinions, beliefs) without providing them new information.