equal
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48 |
48 |
49 \item How is the power of a language defined? (Hint: There are two |
49 \item How is the power of a language defined? (Hint: There are two |
50 rules, one for $\_^0$ and one for $\_^{n+1}$.) |
50 rules, one for $\_^0$ and one for $\_^{n+1}$.) |
51 |
51 |
52 \item Let $A = \{[a], [b], [c], [d]\}$. (1) How many strings |
52 \item Let $A = \{[a], [b], [c], [d]\}$. (1) How many strings |
53 are in $A^4$? (2) Consider the case of $A^4$ where one of |
53 are in $A^4$? (2) Consider also the case of $A^4$ where one of |
54 the strings in $A$ is the empty string, for example $A = |
54 the strings in $A$ is the empty string, for example $A = |
55 \{[a], [b], [c], []\}$. |
55 \{[a], [b], [c], []\}$. |
56 |
56 |
57 \item How many basic regular expressions are there to match |
57 \item How many basic regular expressions are there to match |
58 the string $abcd$? (ii) How many if they cannot include |
58 the string $abcd$? (ii) How many if they cannot include |