토큰,token을 다루는,
언어,language에 대한
연산,operations들 중에서 (language operations)
via
https://www.cs.fsu.edu/~engelen/courses/COP562105/
- Union
$\displaystyle L\cup M=\left\lbrace s \middle| s\in L \text{ or } s\in M \right\rbrace$
- concatenation
$\displaystyle LM=\lbrace xy | x\in L \text{ and } y \in M \rbrace$
- exponentiation
$\displaystyle L^0=\lbrace \varepsilon \rbrace$
$\displaystyle L^i = L^{i-1}L$
- Kleene closure
$\displaystyle L^* = \bigcup_{i=0,\ldots,\infty} L^i$
- Positive closure
$\displaystyle L^+ = \bigcup_{i=1,\ldots,\infty} L^i$
Kleene_closure
Kleene closure
positive_closure
Positive closure