[Tex/LaTex] prevent indentation of a paragraph

indentationlyx

In Lyx, by default most paragraphs are indented (except at beginning of section and after lists). How can I cancel the indentation for specific paragraphs?

Best Answer

Right click in the paragraph, click Paragraph Settings, uncheck Indent Paragraph in the lower left corner of the dialog box. (This does the same as Werner's comment, \noindent is added to the LaTeX source, but you do not need the ERT.)

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Related Solutions

[Tex/LaTex] Paragraph indentation in a list

The enumerate environment removes the paragraph indentation, but you may restore that. Afterwards the paragraphs within enumerate would be indented, but not the first one, like desired. For example, create a myenumerate environment and use this instead:

\newenvironment{myenumerate}{%
  \edef\backupindent{\the\parindent}%
  \enumerate%
  \setlength{\parindent}{\backupindent}%
}{\endenumerate}

It could be done even easier using the enumitem package:

\usepackage{enumitem}
\setenumerate{listparindent=\parindent}

For your convenience, here's a complete example. It uses the first redefiniton, but the two enumitem lines (and the enumerate environment) would give the same result:

\documentclass{article}
\usepackage[english]{babel}
\usepackage{blindtext}
%
\newenvironment{myenumerate}{%
  \edef\backupindent{\the\parindent}%
  \enumerate%
  \setlength{\parindent}{\backupindent}%
}{\endenumerate}

%
\begin{document}
\begin{myenumerate}
\item
  \begin{myenumerate}
    \item \blindtext

         \blindtext
    \item \blindtext
  \end{myenumerate}
\end{myenumerate}
\end{document}

alt text

I recommend to use the enumitem package, it offers many further features for customizing lists.

[Tex/LaTex] When does LaTex add indentation at the start of a paragraph

The short answer is that TeX always indents a new paragraph.

However, in some cases the indentation box is removed:

just after a sectional title (from \chapter, \section, \subsection and so on)
after a list, if there is no blank line between \end{<list>} and the following text

The exception in 1 is lifted if the indentfirst package is used or the main babel language is one where the “indent also after sectional titles” behavior is set.

Here by <list> I mean every environment built around the generic list-making environments: a partial inventory is

itemize
enumerate
description
center
flushleft
flushright
quotation
quote
list
trivlist

(the last two are the most generic).

Display math environments behave similarly: if a blank line follows the display, the ensuing text is taken to be a new paragraph and so the indentation box is added. If no blank line follows, then the indentation box is not inserted in the first place (and not removed as in the previous cases).

What's a new paragraph, for the purpose of this answer?

A blank line (or a \par command) tells TeX that a paragraph must end and so it should be broken into lines. The following text is then taken as a new paragraph, hence indented as said before (but the indentation box is possibly removed).

Note that \\ does not generally end a paragraph, so no indentation box is added after it (or its sibling \newline). However \\ should only be used in an environment where manually ending lines is sensible (flushleft, center, flushright). It's also used in tabular material where it denotes the end of a row.

The indentation box has width \parindent, whose value is determined by the document class or overridden by the user, maybe through some loaded package. Exception: inside lists, the indentation box has width \listparindent (whose value depends on the current list).

Exhortations

Never use \\ to “end paragraphs”. It's not meant for that.
Leave TeX the job of indenting lines. This typographical device has been in use for centuries and helps the reader in better understanding how the text is laid out.

TeXnical details

Strictly speaking, also sectional titles and list items are paragraphs; however, LaTeX treats them in a special way, so they can be excluded from the considerations above. Similarly, \\ in center, flushleft and flushright actually issues \par, so in those environments it behaves the same as a blank line; however the \parindent value is set to zero in such environments.