A regular expression (regex) is a pattern that can be used to match a string of text. They are a standard feature of many programming languages that are used for text-processing purposes (and they have the inconvenient habit of being implemented ever-so-slightly differently in different languages).
D. Karger, und D. Quan. Web Semantics: Science, Services and Agents on the World Wide Web, Selcted Papers from the International Semantic Web Conference, 2004 - ISWC, 2004, Hiroshima, Japan, 07-11 November 2004, 3 (2-3):
147-157(Oktober 2005)