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46 |
46 |
47 \item Given the regular expression $r = (a \cdot b + b)^*$. |
47 \item Given the regular expression $r = (a \cdot b + b)^*$. |
48 Compute what the derivative of $r$ is with respect to |
48 Compute what the derivative of $r$ is with respect to |
49 $a$, $b$ and $c$. Is $r$ nullable? |
49 $a$, $b$ and $c$. Is $r$ nullable? |
50 |
50 |
51 \item (Moved to HW3) |
51 \item Prove that if $r$ is nullable then $r^{\{n\}} \equiv r^{\{..n\}}$. |
52 |
52 |
53 \item Define what is meant by the derivative of a regular |
53 \item Define what is meant by the derivative of a regular |
54 expressions with respect to a character. (Hint: The |
54 expressions with respect to a character. (Hint: The |
55 derivative is defined recursively.) |
55 derivative is defined recursively.) |
56 |
56 |