equal
deleted
inserted
replaced
46 two rules, one for $\_^0$ and one for |
46 two rules, one for $\_^0$ and one for |
47 $\_^{n+1}$.) |
47 $\_^{n+1}$.) |
48 |
48 |
49 \item How many regular expressions are there to match the |
49 \item How many regular expressions are there to match the |
50 string $abc$? (How many if they cannot include |
50 string $abc$? (How many if they cannot include |
51 $\epsilon$ and $\varnothing$? How many if they also are |
51 $\epsilon$ and $\varnothing$? How many if they are also |
52 not allowed to contain stars? How many if they also are |
52 not allowed to contain stars? How many if they are also |
53 not allowed to contain $\_ + \_$?) |
53 not allowed to contain $\_ + \_$?) |
54 |
54 |
55 \item When are two regular expressions equivalent? Can you |
55 \item When are two regular expressions equivalent? Can you |
56 think of instances where two regular expressions are |
56 think of instances where two regular expressions match |
57 equivalent, but it is not so obvious that they are? For |
57 teh same strings, but it is not so obvious that they do? For |
58 example $a + b$ and $b + a$ do not count\ldots they |
58 example $a + b$ and $b + a$ do not count\ldots they |
59 are obviously equivalent. |
59 obviously match the same strings, namely $[a]$ and $[b]$. |
60 |
60 |
61 \end{enumerate} |
61 \end{enumerate} |
62 |
62 |
63 \end{document} |
63 \end{document} |
64 |
64 |