\begin{figure}[p]\caption{{\em An object oriented solution to the N-queens problem}} \xdeno{{\it queen}}{ .ds queens.pl } Each queen checks whether it occupies a legal position with respect to its neighbor. The last queen in the row does not have a neighbor as is indicated by the constant []. The expression row // max delivers row modulo max, where max is the instance variable recording the maximum row number. } \end{figure}