\documentstyle[12pt,twoside]{article}

\newcommand{\problem}{%
  \paragraph{Problem}}
\newcommand(\solution}{%
  \paragraph{Solution}}

\begin{document}


\begin{problems}

%BEGIN Kavita's problems
%END   Kavita's problems

%BEGIN Joe's problems
%END   Joe's problems

%BEGIN Ray's problems
%END   Ray's problems

%BEGIN Ivan's problems (spring '98)
%END   Ivan's problems

%BEGIN George's problems
%END   George's problems

%BEGIN Josh's problems
%END   Josh's problems

%BEGIN Tina's problems
%END   Tina's problems


\end{problems}

\end{document}



