\begin{theorem}[Pythagoras]\label{thm:pyth}
  For a right triangle, $a^2 + b^2 = c^2$.
\end{theorem}

\begin{proof}
  The proof follows from the figure in \autoref{thm:pyth}.
\end{proof}

\begin{remark}
  Theorem-like environments may carry an optional title argument.
\end{remark}
