# Increasing depth of document

I am trying to type by using amsart. I want numbering of the definitions, lemma theorem etc should be of the form x.y.z, where x is section, y subsection and z the actual number of the theorem. I ave used \setcounter{secnumdepth}{4} but it does not seem to be working. (Moreover I do not want any table of contents). Please help.

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secnumdepth is something different; it determines which section headings should receive numbers, not the numbers that they receive.

When you define your definitions, lemmas, etc, you have the option to determine which counters they inherit; for example,

\newtheorem{definition}{Definition}[subsection]


will define the definition environment to use the subsection counter. Here's a complete MWE:

% arara: pdflatex
\documentclass{amsart}
\usepackage{lipsum}

\newtheorem{definition}{Definition}[subsection]
\newtheorem{lemma}{Lemma}[subsection]

\begin{document}

\begin{definition}
\lipsum[1]
\end{definition}
\begin{lemma}
\lipsum[1]
\end{lemma}

\end{document}

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While this is a correct answer to the question, I'd recommend not to number statements by subsection, which makes it impossible not to use subsections; moreover, the number will be very long: <chapter>.<section>.<subsection>.<statement> –  egreg Apr 26 '14 at 9:53