For discussion today: How to deal with MPI_Comm_compare(ep_comm[0], ep_comm[1], &result). Where ep_comm is an array of handles to different ranks in the same endpoints comm. Currently, MPI defines: IDENT, CONGRUENT, SIMILAR, and UNEQUAL. None are a good match, seems like we need a new one for the case where they are the same communicator and same group (IDENT), but represent a different rank in the comm.

I suggest MPI_ALIASED to describe this situation. Jeff -- Jeff Hammond [email protected]