Error when using \begin{RÉSUMÉ}

Question

I write a paper in French, I add a package \usepackage[english,francais]{babel} to use a French but when I write:

\begin{RÉSUMÉ} abstract in french \end{RÉSUMÉ}

I get the error:

! LaTeX Error: Environment R\IeC {\'E}SUM\IeC {\'E} undefined.

and when I use:

\begin{R\'ESUM\'E} résumé en français \end{R\'ESUM\'E}

I get the same error:

! LaTeX Error: Environment R\'ESUM\'E undefined.

Answer 1

Changing your language in babel doesn't change the language of the commands, it only changes the hyphenation patterns, the printed titles of e.g. the table of contents or the abstract, and, in the case of french, also the punctuation spacing (You can see below that there's space before the exclamation mark). Thus, you'll still need to use abstract as the environment's name.

While francais will work as an option for babel, I'd recommend using french instead (which does exactly the same), just so you won't get confused with the languages and keep all macros in English. Thanks to Ulrike for clarifying in the comments.

\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage[english,french]{babel}
\usepackage[T1]{fontenc}

\title{Mon titre}
\author{C'est moi}

\begin{document}

\maketitle

\begin{abstract}
Bonjour.
\end{abstract}

\tableofcontents

\section{Et voilà!}

\subsection{Bon alors}

C'est grandiose!

\end{document}

Answer 2

You can't use non-English letters in macro and environment names. The special characters are often implemented as active characters, i.e. characters which are actually macros. As you can see in the error message É is expanded to \IeC {\'E}. Such non-expandable macro can't be used in environment names.

If you want to define a RÉSUMÉ environment yourself you should use RESUME instead. Note that the babel package does not translate the names of the macros and environments, but provides hyphenation patterns and language related macros and settings, like e.g. French quotes. The default environment for this is abstract. It might be possible to translate such names to French for people which have issues with English, but even then non-English letters are a no-go.

---

If you want the abstract title instead by RÉSUMÉ you need to use the abstract environment nevertheless, but switch the language to french. The exact name can also be redefined manually:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage[english,french]{babel}

%\renewcommand{\abstractname}{RÉSUMÉ}
\begin{document}

\begin{abstract}
    French abstract ...
\end{abstract}

\selectlanguage{english}
\begin{abstract}
    English abstract ...
\end{abstract}

text text ...

\end{document}

Answer 3

Using babel won't translate the user interface! All the macro and environment names will stay the same. I don't know whether there are packages for doing this, but babel does not.

ConTeXt allows localising the user interface AFAIK.

Answer 4

You should not translate environment names into French, any more than you would translate \begin and \end. Use \begin{abstract} and \end{abstract}. It is possible to change the heading from 'Abstract' to 'Resume' in your document, but how you achieve this depends on the document class that you are using.