hws/hw01.tex
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    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