Kleene star

Unary operation on string sets

In mathematical logic and computer science, the Kleene star is a unary operation, either on sets of strings or on sets of symbols or characters. In mathematics, it is more commonly known as the free monoid construction. The application of the Kleene star to a set is written as . It is widely used for regular expressions, which is the context in which it was introduced by Stephen Kleene to characterize certain automata, where it means "zero or more repetitions".If is a set of strings, then is defined as the smallest superset of that contains the empty string and is closed under the string concatenation operation. If is a set of symbols or characters, then is the set of all strings over symbols in , including the empty string .

This keyword could refer to multiple things. Here are some suggestions: