ABSTRACT
This chapter summarizes notation and mathematical facts used in the rest of the book. The most important of these is ‘iff’ which means if and only if.
Sets of objects will usually be denoted by capital letters, A, S, T for example, while their members by lower case letters (English or Greek). The empty set is denoted ∅. If an object x belongs to a set S we write x ∈ S and if it does not we write x ∈ S. The set of objects not in a given set S is called the complement of S and denoted Sc. Frequently our sets will be described by some property shared by all its elements. We will write this in the form {x: x has property P}.
