proposed by | Alan Frisch, Chris Jefferson, and Ian Miguel frisch@cs.york.ac.uk, caj@cs.york.ac.uk, ianm@cs.york.ac.uk |
/a_11 ... a_1k\ /(a_11)^2 ... (a_1k)^2\ det ( ... ... ... ) = 1, det ( ... ... ... ) = +/- 1 \a_k1 ... a_kk/ \(a_k1)^2 ... (a_kk)^2/where the a_ii are integers not equal to plus or minus 1, and `det' denotes the determinant of a matrix. The solutions to this problem are significant in classifying certain types of topological spaces. Guy discusses a variant where 0 entries are also disallowed and the sign of both determinants must be positive.