# formal

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**Formal wear**— Western dress codes Formal wear Formal Semi formal Informal Smart casual Business casual Casual Active attire Formal wear (US, Canada) and formal dress (UK, Australia, New Zealand, and other Commonwealth Realms) are the general terms for clothing …122

**Formal power series**— In mathematics, formal power series are devices that make it possible to employ much of the analytical machinery of power series in settings that do not have natural notions of convergence. They are also useful, especially in combinatorics, for… …123

**Formal methods**— In computer science and software engineering, formal methods are particular kind of mathematically based techniques for the specification, development and verification of software and hardware systems.cite web|author=R. W. Butler|title=What is… …124

**Formal system**— In formal logic, a formal system (also called a logical system,Audi, Robert (Editor). The Cambridge Dictionary of Philosophy . Second edition, Cambridge University Press, 1999. ISBN 978 0521631365 (hardcover) and ISBN 978 0521637220 (paperback).] …125

**Formal interpretation**— A formal interpretation [http://books.google.com/books?id=weKqT3ka5g0C pg=PA74 lpg=PA74 dq=%22Formal+interpretation%22+%22formal+language%22 source=web ots=pLN ms7Wi2 sig=P JqwdzOqLcX4nMpP64qmacnkDU hl=en#PPA74,M1 Cann Ronnie, Formal Semantics:… …126

**Formal proof**— See also: mathematical proof, proof theory, and axiomatic system A formal proof or derivation is a finite sequence of sentences (called well formed formulas in the case of a formal language) each of which is an axiom or follows from the… …127

**Formal language**— A formal language is a set of words , i.e. finite strings of letters , or symbols . The inventory from which these letters are taken is called the alphabet over which the language is defined. A formal language is often defined by means of a… …128

**Formal science**— A formal science is a theoretical study that is concerned with theoretical formal systems, for instance, logic, mathematics, systems theory and the theoretical branches of computer science, information theory, economics, statistics, and… …