-Group::Group(int n) : size_(n), rank_to_actor_map_(size_, nullptr), rank_to_index_map_(size_, MPI_UNDEFINED), index_to_rank_map_(size_, MPI_UNDEFINED)
+Group::Group(int n) : size_(n), rank_to_actor_map_(size_, nullptr), index_to_rank_map_(size_, MPI_UNDEFINED)