handouts/notation.tex
changeset 332 4755ad4b457b
parent 266 ae039d6ae3f2
child 398 c8ce95067c1a
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331:a2c18456c6b7 332:4755ad4b457b
    17 
    17 
    18 The most important concept in this module are strings. Strings
    18 The most important concept in this module are strings. Strings
    19 are composed of \defn{characters}. While characters are surely
    19 are composed of \defn{characters}. While characters are surely
    20 a familiar concept, we will make one subtle distinction in
    20 a familiar concept, we will make one subtle distinction in
    21 this module. If we want to refer to concrete characters, like
    21 this module. If we want to refer to concrete characters, like
    22 \code{a}, \code{b} and so on, we use a typewriter font.
    22 \code{a}, \code{b}, \code{c} and so on, we use a typewriter font.
    23 Accordingly if we want to refer to the concrete characters of
    23 Accordingly if we want to refer to the concrete characters of
    24 my email address we shall write
    24 my email address we shall write
    25 
    25 
    26 \begin{center}
    26 \begin{center}
    27 \pcode{christian.urban@kcl.ac.uk}
    27 \pcode{christian.urban@kcl.ac.uk}
    35 \end{center}
    35 \end{center}
    36 
    36 
    37 
    37 
    38 \noindent But often we do not care which particular characters
    38 \noindent But often we do not care which particular characters
    39 we use. In such cases we use the italic font and write $a$,
    39 we use. In such cases we use the italic font and write $a$,
    40 $b$ and so on for characters. Therefore if we need a
    40 $b$, $c$ and so on for characters. Therefore if we need a
    41 representative string, we might write
    41 representative string, we might write
    42 
    42 
    43 \begin{equation}\label{abracadabra}
    43 \begin{equation}\label{abracadabra}
    44 abracadabra
    44 abracadabra
    45 \end{equation}
    45 \end{equation}
    65 double quotes indicate that we are dealing with a string. But
    65 double quotes indicate that we are dealing with a string. But
    66 since we regard strings as lists of characters we could also
    66 since we regard strings as lists of characters we could also
    67 write this string as
    67 write this string as
    68 
    68 
    69 \[
    69 \[
    70 [\text{\it h, e, l, l, o}]
    70 [\text{\it h, e, l, l, o}] \;\;\text{or simply}\;\; \textit{hello}
    71 \]
    71 \]
    72 
    72 
    73 \noindent The important point is that we can always decompose
    73 \noindent The important point is that we can always decompose
    74 such strings. For example, we will often consider the first
    74 such strings. For example, we will often consider the first
    75 character of a string, say $h$, and the ``rest'' of a string
    75 character of a string, say $h$, and the ``rest'' of a string