equal
deleted
inserted
replaced
10 |
10 |
11 \begin{enumerate} |
11 \begin{enumerate} |
12 \item What is a regular language? |
12 \item What is a regular language? |
13 |
13 |
14 \item Assume you have an alphabet consisting of the letters $a$, $b$ and $c$ only. |
14 \item Assume you have an alphabet consisting of the letters $a$, $b$ and $c$ only. |
15 (a) Find a regular expression that recognises the two strings $ab$ and $ac$. (b) |
15 (1) Find a regular expression that recognises the two strings $ab$ and $ac$. (2) |
16 Find a regular expression that matches all strings \emph{except} these two strings. |
16 Find a regular expression that matches all strings \emph{except} these two strings. |
17 Note, you can only use regular expressions of the form |
17 Note, you can only use regular expressions of the form |
18 \begin{center} |
18 \begin{center} |
19 $r ::= \varnothing \;|\; \epsilon \;|\; c \;|\; r_1 + r_2 \;|\; r_1 \cdot r_2 \;|\; r^*$ |
19 $r ::= \varnothing \;|\; \epsilon \;|\; c \;|\; r_1 + r_2 \;|\; r_1 \cdot r_2 \;|\; r^*$ |
20 \end{center} |
20 \end{center} |