[Tex/LaTex] Nested enumeration numbering

#enumeratelistsnestingnumbering

I write homework assignments in LaTex and the assignments are always divided into subparts (i.e. Problem 1 is divided into 1.1, 1.2, 1.3, …). Currently what I do is I have nested enumerations, but the numbering isn't exactly what I'd like. To number the subparts, I am currently using:

\renewcommand{\labelenumii}{\arabic{enumii}.}

However, this produces

1.
2.
...

and what I'd like it to be is 

1.1
1.2
...

Is there anyway to do this?

Best Answer

Use

\renewcommand{\labelenumii}{\theenumii}
\renewcommand{\theenumii}{\theenumi.\arabic{enumii}.}

to change the way nested enumerations are set (without brackets ()) and in a sub-enumeration form that is \arabic:

enter image description here

\documentclass{article}
\renewcommand{\labelenumii}{\theenumii}
\renewcommand{\theenumii}{\theenumi.\arabic{enumii}.}
\begin{document}
\begin{enumerate}
  \item First
  \begin{enumerate}
    \item Second
    \item Third
  \end{enumerate}
  \item Fourth
\end{enumerate}
\end{document}​

The enumitem is actually the de-facto list processing/setting package. Here's such a take on your enumeration:

\documentclass{article}
\usepackage{enumitem}% http://ctan.org/pkg/enumitem
\begin{document}
\begin{enumerate}
  \item First
  \begin{enumerate}[label*=\arabic*.]
    \item Second
    \item Third
  \end{enumerate}
  \item Fourth
\end{enumerate}
\end{document}​

label* appends the suggested key-value to the parent label. Of course, global setting is also possible.

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