[1XReferences[0X [[20XBH82[15X] [16XBrown, R. and Huebschumann, J.[15X ([1m[31mBrown, R. and Thickstun, T. L.[15X, Eds.), [17XIdentities Among Relations[15X, in Low-Dimensional Topology, Cambridge University Press, London Math. Soc. Lecture Note Series, [19X46[15X (1982), 153-202. [[20XBS99[15X] [16XBrown, R. and Razak Salleh, A.[15X, [17XOn the computation of identities among relations and of free crossed resolutions of groups[15X, [18XLondon Math. Soc. J. Comput. Math.[15X, [19X2[15X (1999), 28-61. [[20XHey99[15X] [16XHeyworth, A.[15X, [17XApplications of Rewriting Systems and Groebner Bases to Com puting Kan Extensions and Identities Among Relations[15X, Ph.{D}.~thesis, University of Wales, Bangor (1999). [[20XHW03[15X] [16XHeyworth, A. and Wensley, C. D.[15X ([1m[31mCampbell, C. M., Robertson, E. F. and Smith, G. C.[15X, Eds.), [17XLogged rewriting and identities among relators[15X, in Groups St Andrews 2001 in Oxford, Cambridge University Press, London Math. Soc. Lecture Note Series, [19X304[15X (2003), 256-276. -------------------------------------------------------