I used MPI_Comm_split to split the default MPI communicator.If initially there were 10 processes in default communicator ,MPI_COMM_WORLD and ,say, their ranks were identified by id_original. The new communicator consisted of 4 processes with id_original 6,7,8,9.These processes will have ranks defined by , say , id_new in the new communicator. What will be the relation between ranks of processes in these two communicators. Will the processes with id_original 6,7,8,9 will have new ranks 0,1,2,3 respectively in the new communicator or the ordering might be different?