The MPI-2 standard says (see bottom of <http://www.mpi-forum.org/docs/mpi-20-html/node120.htm#Node120>)
MPI_WIN_GET_GROUP returns a duplicate of the group of the communicator used to create the window. associated with win. The group is returned in group. Pease, note the 'duplicate' ... Well, it seems OMPI (v1.2 svn) is not returning a duplicate, comparing the handles with == C operator gives true. Can you confirm this? Should the word 'duplicate' be interpreted as 'a new reference to' ? As reference, MPICH2 seems to return different handles. Anyway, I think the standard needs to be corrected/clarified. Perhaps the strict 'duplication' does not make any sense. Regards, and sorry me for raising again such low-level, corner-cases ... -- Lisandro Dalcín --------------- Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC) Instituto de Desarrollo Tecnológico para la Industria Química (INTEC) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) PTLC - Güemes 3450, (3000) Santa Fe, Argentina Tel/Fax: +54-(0)342-451.1594