\usepackage {hyperref}
\usepackage {exercise}
\edef\hyper@quote{\string"}
\edef\hyper@sharp{\string#}
\def \softlink #1#2{\special 
  {html:<A href=\hyper@quote\hyper@sharp#1\hyper@quote>}#2\special
  {html:</A>}}
\def \softtarget #1#2{\special
  {html:<A name=\hyper@quote#1\hyper@quote>}#2\special
  {html:</A>}}

\newtheorem{theorem}{Theorem}
\newtheorem{lemma}{Lemma}
\newenvironment{proof}{Proof:}{}
