User:Jshflynn/Definition:Kleene plus

Definition
Let $\Sigma$ be an alphabet.

Let $V$ be a subalphabet of $\Sigma$.

Then the Kleene plus of $V$ is denoted $V^+$ and defined:


 * $\ds \bigcup_{i \mathop \in \N_{>0} } V^i$

Also known as
Some authors call this:


 * Semigroup closure