example cluster_0 batch_0 cluster_1 batch_1 cluster_2 batch_2 cluster_3 batch_3 create_a create_a modify_a modify_a create_a->modify_a A create_c create_c create_a->create_c A reduce_abc_to_d reduce_abc_to_d create_a->reduce_abc_to_d A create_b create_b create_b->modify_a B create_b->create_c B create_b->reduce_abc_to_d B create_c->reduce_abc_to_d C