In this Dictionary of Mathematic, key ideas, terms and concepts are clearly explained in an accessible and easy-to-use format.Each entry begins with a short definition and is followed by an explanation and/or worked example. The more complex and important the term, the more detailed the entry.In writing each entry, the authors kept three questions in mind: what does the entry mean? why do I need to know it? how is it used? The method follows the familiar concept that knowledge in mathematics consists of "concept, context, and skill".