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40 of the strings is the empty string. How many strings are in $A \,@\, B$? |
40 of the strings is the empty string. How many strings are in $A \,@\, B$? |
41 |
41 |
42 \item How is the power of a language defined? (Hint: There are two |
42 \item How is the power of a language defined? (Hint: There are two |
43 rules, one for $\_^0$ and one for $\_^{n+1}$.) |
43 rules, one for $\_^0$ and one for $\_^{n+1}$.) |
44 |
44 |
45 \item Let $A = \{[], [a], [b], [c]\}$. How many strings are in $A^4$? |
45 \item Let $A = \{[a], [b], [c], [d]\}$. How many strings are in $A^4$? |
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46 Consider the case of $A^4$ where one of the strings in $A$ is the |
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47 empty string. |
46 |
48 |
47 \item How many regular expressions are there to match the string |
49 \item How many regular expressions are there to match the string |
48 $abc$? How many if they cannot include $\epsilon$ and $\varnothing$? |
50 $abc$? How many if they cannot include $\epsilon$ and $\varnothing$? |
49 How many if they are also not allowed to contain stars? How many if |
51 How many if they are also not allowed to contain stars? How many if |
50 they are also not allowed to contain $\_ + \_$? |
52 they are also not allowed to contain $\_ + \_$? |