Models of Computation MT23, Languages
Flashcards
If $A$ and $B$ are languages, what is $A \cdot B$?
\[A \cdot B = \{xy : x\in A, y \in B\}\]
i.e. concatenation.
If $A$ is a language, what is $A^\star$?
\[\{x _ 1 \cdots x _ k : k \ge 0, x _ i \in A\} \]
How might you more informally write out $A^\star = \{x _ 1 \cdots x _ k : k \ge 0, x _ i \in A\}$?
\[\{\epsilon\} \cup A \cup (AA) \cup (AAA) \cup \cdots\]