A computational model is a framework for doing computations according to
certain specified rules on some input data. These models come for
example from automata theory, formal language theory, logic, or circuit
theory. The computational power of such a model can be judged by
evaluating certain problems with respect to that model.
The theory of computations is the study of the inherent difficulty of
computational problems, that is, their computational complexity. This
monograph analyzes the computational complexity of the satisfiability,
equivalence, and almost-equivalence problems with respect to various
computational models. In particular, Boolean formulas, circuits, and
various kinds of branching programs are considered.