]> 1 1 A point in the range of a function at which it is undefined or not continuous [Wiktionary] An equation is a mathematical statement, in symbols, that two things are exactly the same (or equivalent). [Wikipedia] 1 In topology and related areas of mathematics a net or Moore-Smith sequence is a generalization of a sequence, intended to unify the various notions of limit and generalize them to arbitrary topological spaces. Limits of nets accomplish for all topological spaces what limits of sequences accomplish for first-countable spaces such as metric spaces. An operation is an action or procedure which produces a new value from one or more input values. [Wikipedia] 0 In mathematics, the concept of a relation is a generalization of 2-place relations, such as the relation of equality, less than, greater than, etc.. [Wikipedia] true