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the description environment or a special list environment.
46
TUTORIAL VI


DISPLAYED TEXT


There are many instances in a document when we want to visually separate a portion
of text from its surrounding material. One method of doing this is to typeset the distin-
guished text with added indentation. It is called displaying. LTEX has various constructs
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for displaying text depending the nature of the displayed text.

BORROWED
VI.1. WORDS

Quotations are often used in a document, either to add weight to our arguments by
referring to a higher authority or because we ¬nd that we cannot improve on the way
an idea has been expressed by someone else. If the quote is a one-liner, we can simply
include it within double-quotes and be done with it (remember how to use quotes in
TEX?) But if the quotation is several lines long, it is better to display it. Look at the
following example:

Some mathematicians elevate the spirit of Mathematics to a kind of intellectual aesthetics. It
is best voiced by Bertrand Russell in the following lines.
The true spirit of delight, the exaltation, the sense of being more than man, which
is the touchstone of the highest excellence, is to be found in Mathematics as surely
as in poetry.. . . Real life is, to most men, a long second best, a perpetual compro-
mise between the ideal and the possible; but the world of pure reason knows no
compromise, no practical limitations, no barriers to the creative activity embody-
ing in splendid edi¬ces the passionate aspiration after the perfect, from which all
great work springs.
Yes, to men like Russell, Mathematics is more of an art than science.


This was type set as shown below
Some mathematicians elevate the spirit of Mathematics to a kind of
intellectual aesthetics. It is best voiced by Bertrand Russell in the
following lines.
\begin{quote}
The true spirit of ................................from which
all great work springs.
\end{quote}

Note that here we give instructions to TEX to typeset some material in a separate
paragraph with additional indentation on either side and indicate the start and end of
material requiring special treatment, by means of the commands
\begin{quote} ... \end{quote}


47
48 DISPLAYED TEXT
VI.


This is an example of what is known in LTEX parlance as an environment. Environ-
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ments are used to delimit passages requiring special typographic treatments and to give
instructions to LTEX on how to typeset it. The general form of an environment is of the
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form
\begin{name} ... \end{name}
where name is the name of the environment and signi¬es to LTEX the type of typographic
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treatment required (deliberate attempt at a pun, that).
The quoted part in this example is a single paragraph. If the quotation runs into
several paragraphs, we must use the quotation environment, by enclosing the quotation
within \begin{quotation} and \end{quotation}. As usual, paragraphs are separated by
blank lines while typing the source ¬le.

POETRY
VI.2. IN TYPESETTING

LTEX can write poetry...well almost; if you write poems, TEX can nicely typeset it for
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you. (I have also heard some TEX wizards saying Knuth™s code is sheer poetry!) Look at
the passage below:

Contrary to popular belief, limericks are not always ribald. Some of them contain mathemati-
cal concepts:
A mathematician once con¬ded
¨
That a Mobius band is one sided
You™ll get quite a laugh
If you cut it in half
For it stays in one piece when divided
There is an extension of this to Klein™s bottle also.

This was typeset as follows:
Contrary to popular belief, ... tried their hands at it:
\begin{verse}
A mathematician confided\\
A M\"obius band is one sided\\
You™ll get quite a laugh\\
If you cut it in half\\
For it stays in one piece when divided
\end{verse}
There is an extension of this to Klein™s bottle also.


Note that line breaks are forced by the symbol \\. Different stanzas are separated
in the input by one (or more) blank lines. If you do not want TEX to start a new page at
a particular line break (if you want to keep rhyming couplets together in one page, for
example), then use \\* instead of plain \\. Again, if you want more space between lines
than what LTEX deems ¬t, then use \\ with an optional length as in \\[5pt] which adds
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an extra vertical space of 5 points between the lines. You can also type \\*[5pt], whose
intention should be obvious by now.

MAKING
VI.3. LISTS

Lists are needed to keep some semblance of order in a chaotic world and LTEX helps us
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to typeset them nicely. Also, there are different kinds of lists available by default and if
49
MAKING
VI.3. LISTS


none of them suits your need, there are facilities to tweak these or even design your own.
Let us ¬rst have a look at the types of lists LTEX provides.
A


Saying it with bullets
VI.3.1.

The itemize environment gives us a bullet-list. For example it produces something like
this:

One should keep the following in mind when using TEX
• TEX is a typesetting language and not a word processor
• TEX is a program and and not an application
• Theres is no meaning in comparing TEX to a word processor, since the design purposes
are different
Being a program, TEX offers a high degree of ¬‚exibility.


The input which produces this is given below:
One should keep the following in mind when using \TeX
\begin{itemize}
\item \TeX\ is a typesetting language and not a word processor
\item \TeX\ is a program and and not an application
\item Theres is no meaning in comparing \teX\ to a word processor, since the design
purposes are different
\end{itemize}
Being a program, \TeX\ offers a high degree of flexibility.

The \begin{itemize} ... \end{itemize} pair signi¬es we want a bullet-list of the
enclosed material. Each item of the list is speci¬ed by (what else?) an \item command.
We can have lists within lists. For example:

One should keep the following in mind when using TEX
• TEX is a typesetting language and not a word processor
• TEX is a program and and not an application
• Theres is no meaning in comparing TEX to a word processor, since the design purposes
are different
• TEX is the natural choice in one of these situations
“ If we want to typeset a document containing lot of Mathematics
“ If we want our typed document to look beautiful
Being a program, TEX offers a high degree of ¬‚exibility.

It is produced by the input below:
One should keep the following in mind when using \TeX
\begin{itemize}
\item \TeX\ is a typesetting language and not a word processor
\item \TeX\ is a program and and not an application
\item Theres is no meaning in comparing \TeX\ to a word processor, since the design
purposes are different
\item \TeX\ is the natural choice in one of these situations
\begin{itemize}
\item If we want to typeset a document containing lot of Mathematics
50 DISPLAYED TEXT
VI.


\item If we want our typed document to look beautiful
\end{itemize}
\end{itemize}
Being a program, \TeX\ offers a high degree of flexibility.

The itemize environment supports four levels of nesting. The full list of labels for the
items (˜bullets™ for the ¬rst level, ˜dashes™ for the second and so on) is as shown below

• The ¬rst item in the ¬rst level
• the second item in the ¬rst level
“ The ¬rst item in the second level
“ the second item in the second level
— The ¬rst item in the third level
— the second item in the third level
· The ¬rst item in the fourth level
· the second item in the fourth level


Not satis¬ed with these default labels? How about this one?

First item of a new list
Second item

It was produced by the following input:
{\renewcommand{\labelitemi}{$\triangleright$}
\begin{itemize}
\item First item of a new list
\item Second item
\end{itemize}}

Several things need explanation here. First note that the ¬rst level labels of the
itemize environment are produced by the (internal and so invisible to the user) command
\labelitemi and by default, this is set as \textbullet to produce the default ˜bullets™.
What we do here by issuing the \renewcommand is to override this by a choice of our own
namely $\triangleright$ which produces the little triangles in the above list. Why the
braces { and } (did you notice them?) enclosing the whole input? They make the effect
of the \renewcommand local in the sense that this change of labels is only for this speci¬c
list. Which means the next time we use an itemize environment, the labels revert back
to the original ˜bullets™. If we want the labels to be changed in the entire document, then
remove the braces.
What if we want to change the second level labels? No problem, just change the
\labelitemii command, using a symbol of our choice. The third and fourth level labels
are set by the commands (can you guess?) \labelitemiii and \labelitemiv. Look at the
following example.
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WHEN
VI.4. ORDER MATTERS



 The ¬rst item in the ¬rst level
 the second item in the ¬rst level
 The ¬rst item in the second level
 the second item in the second level
 The ¬rst item in the third level
 the second item in the third level
 The ¬rst item in the fourth level
 the second item in the fourth level

Here the labels are chosen from the PostScript ZapfDingbats font. We will have to use
the package pifont, by including the line \usepackage{pifont} in our document preamble
to access them. The source of the above output is
\renewcommand{\labelitemi}{\ding{42}}
\renewcommand{\labelitemii}{\ding{43}}
\renewcommand{\labelitemiii}{\ding{44}}
\renewcommand{\labelitemiv}{\ding{45}}
\begin{itemize}
\item The first item in the first level
\item the second item in the first level
\begin{itemize}
\item The first item in the second level
\item the second item in the second level
\begin{itemize}
\item The first item in the third level
\item the second item in the third level
\begin{itemize}
\item The first item in the fourth level
\item the second item in the fourth level
\end{itemize}
\end{itemize}
\end{itemize}
\end{itemize}}




WHEN
VI.4. ORDER MATTERS

When the order of the items in a list is important, we need a list which speci¬es this order.
For example, consider this

The three basic steps in producing a printed document using LTEX are as follows
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1. Prepare a source ¬le with the extension tex
2. Compile it with LTEX to produce a dvi ¬le
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3. Print the document using a dvi driver

Such a numbered list is produced by the enumerate environment in LTEX. The above list
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was produced by the following source.
\begin{enumerate}
\item prepare a source file with the extension "tex"
52 DISPLAYED TEXT
VI.


\item Compile it with \LaTeX to produce a "dvi" file
\item Print the document using a "dvi" driver
\end{enumerate}

As in the case of itemize environment, here also four levels of nesting are supports.
The example below shows the labels used for different levels.

1. The ¬rst item in the ¬rst level
2. the second item in the ¬rst level
(a) The ¬rst item in the second level
(b) the second item in the second level
i. The ¬rst item in the third level
ii. the second item in the third level
A. The ¬rst item in the fourth level
B. the second item in the fourth level

How about customizing the labels? Here there is an additional complication in that
the labels for items in the same level must follow a sequence (such as 1,2,3,. . . for the
¬rst level, (a), (b), (c),. . . for the second and so on, by default). There is a method for
doing it, but it will take us into somewhat deeper waters. Fortunately, there is a package
enumerate by David Carlisle, which makes it easy. So if we want

The three basic steps in producing a printed document using LTEX are as follows:
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Step 1. Prepare a source ¬le with the extension tex
Step 2. Compile it with LTEX to produce a dvi ¬le
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i. Use a previewer (such as xdvi on X Window System) to view the output
ii. Edit the source if needed
iii. Recompile
Step 3. Print the document using a dvi driver (such as dvips)

just type the input as follows
The three basic steps in producing a printed document
using \LaTeX\ are as follows:
\begin{enumerate}[\hspace{0.5cm}Step 1.]
\item Prepare a source file with the extension "tex"
\item Compile it with \LaTeX to produce a "dvi" file
\begin{enumerate}[i.]
\item Use a previewer (such as "xdvi" on
\textsf{X Window System}) to view the output
\item Edit the source if needed
\item Recompile
\end{enumerate}
\item Print the document using a "dvi" driver
(such as "dvips")
\end{enumerate}

As you can see, the labels Step 1, Step 2 and Step 3 are produced by the optional ar-
gument Step 1 within square brackets immediately following the ¬rst \begin{enumerate}
command and the labels i, ii, iii for the second level enumeration are produced by the
optional [i] following the second \begin{enumerate}. So, what is \hspace{0.5cm} doing
in the ¬rst optional argument? It is to provide an indentation at the left margin of the
¬rst level items, which the enumerate environment does not produce by default.
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WHEN
VI.4. ORDER MATTERS


We can add further embellishments. For example, if we want the labels in the
¬rst level of the above example to be in boldface, just change the optional argument
[\hspace{0.5cm} Step 1] to [\hspace{0.5cm}\bfseries Step 1]. This produces:


The three basic steps in producing a printed document using LTEX are as follows:
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Step 1 Prepare a source ¬le with the extension tex
Step 2 Compile it with LTEX to produce a dvi ¬le
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(a) Use a previewer (such as xdvi on X Window System) to view the output
(b) Edit the source if needed
(c) Recompile
Step 3 Print the document using a dvi driver (such as dvips)


Some care must be taken when we give options like this. Suppose we want to pro-
duce something like this

Addition of numbers satis¬es the following conditions:
(A1) It is commutative
(A2) It is associative
(A3) There is an additive identity
(A4) Each number has an additive inverse

If we give the option [\hspace{1cm}(A1)] as in
Addition of numbers satisfies the following conditions:
\begin{enumerate}[\hspace{1cm}(A1)]
\item It is commutative
\item It is associative
\item There is an additive identity
\item Each number has an additive inverse
\end{enumerate}

Then we get the (somewhat surprising) output

(11) It is commutative
(22) It is associative
(33) There is an additive identity
(44) Each number has an additive inverse

What happened? In the enumerate package, the option [A] signi¬es that we want the
labels to be named in the sequence A, B, C,. . . ,Z (the upper case Roman alphabet) and
the option [1] signi¬es we want them as 1,2,3,. . . (the Arabic numerals). Other signi¬ers
are [a] for lowercase Roman letters, [I] for uppercase Roman numerals and [i] for
lowercase Roman numerals. So, if we use any one of these in the optional argument with
some other purpose in mind, then enclose it in braces. Thus the correct input to generate
the above example is

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