Lenguajes automatas

 Un autómata finito no determinista (AFN) es una máquina abstracta que sirve para reconocer lenguajes, como el autómata finito determinista (AFD), pero con una diferencia clave: en un AFN, desde un estado y con un símbolo de entrada, pueden existir varias opciones de a qué estado moverse , o incluso ninguna. En otras palabras, es como si el autómata pudiera "elegir" entre varios caminos posibles.

 

 

 

 A regular expression (shortened as regex or regexp), sometimes referred to as rational expression, is a sequence of characters that specifies a match pattern in text. Usually, such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation. Regular expression techniques are developed in theoretical computer science and formal language theory. The concept of regular expressions began in the 1950s, when the American mathematician Stephen Cole Kleene formalized the concept of a regular language. They came into common use with Unix text-processing utilities. Different syntaxes for writing regular expressions have existed since the 1980s, one being the POSIX standard and another, widely used, being the Perl syntax.