\documentclass{rtaloop}
\rtalabel{smallorder-combinators-word}


\begin{document}
\begin{problem}{Richard Statman}{\cite{statman:rta2000}}{July 2000}

\begin{abstract}
Is the word problem for all proper combinators of order smaller than 3
decidable?
\end{abstract}

The order of a proper combinator is the number of variables on
the left hand side of its defining equation. For instance, the $K$
combinator has order 2. Is the word problem for all proper
combinators of order smaller than 3 decidable? See
\cite{statman:rta2000} for related results.

A related question is the word problem for the $S$-combinator (of
order 3), see \rtaref{Scomb-word}.

\end{problem}
\end{document}