20 If you want to follow the code I present during the |
20 If you want to follow the code I present during the |
21 lectures, read the handout about Scala. |
21 lectures, read the handout about Scala. |
22 |
22 |
23 \item {\bf (Optional)} Have a look at the crawler programs. |
23 \item {\bf (Optional)} Have a look at the crawler programs. |
24 Can you find a usage for them in your daily programming |
24 Can you find a usage for them in your daily programming |
25 life? Can you improve them? (For example in cases there |
25 life? Can you improve them? For example in cases there |
26 are links that appear on different recursion levels, the |
26 are links that appear on different recursion levels, the |
27 crawlers visit such web-pages several times. Can this be |
27 crawlers visit such web-pages several times. Can this be |
28 avoided?) |
28 avoided? Also, the crawlers flag as problematic any page |
|
29 that gives an error, but probably only 404 Not Found |
|
30 errors should be flagged. Can you change that?) |
29 |
31 |
30 \item Read the handout of the first lecture and the handout |
32 \item Read the handout of the first lecture and the handout |
31 about notation. Make sure you understand the concepts of |
33 about notation. Make sure you understand the concepts of |
32 strings and languages. In the context of the CFL-course, |
34 strings and languages. In the context of the CFL-course, |
33 what is meant by the term \emph{language}? |
35 what is meant by the term \emph{language}? |
34 |
36 |
35 \item Give the definition for regular expressions---this is an |
37 \item Give the definition for regular expressions---this is an |
36 inductive datatype. What is the |
38 inductive datatype. What is the |
37 meaning of a regular expression? (Hint: The meaning is |
39 meaning of a regular expression? (Hint: The meaning is |
38 defined recursively.) |
40 defined recursively.) |
39 |
41 |
40 \item Assume the concatenation operation of two strings is |
42 \item Assume the concatenation operation of two strings is |