Combinations
Coupling
[ ( π 1 ± ⊗ π 2 ± ) i ⊕ ( π 1 ± ⊗ π 2 ± ) j ]
coupling of I˚ degree
{ ( π 1 ± ⊗ π 2 ± ) i ⊕ [ ( π 1 ± ⊗ π 2 ± ) j ⊕ ( π 1 ± ⊗ π 2 ± ) k ] }
coupling of II˚ degree
[ ( π 1 ± ⊗ π 2 ± ) i ⊕ ( π 1 ± ⊗ π 2 ± ) j ] ⊕ [ ( π 1 ± ⊗ π 2 ± ) k ⊕ ( π 1 ± ⊗ π 2 ± ) r ]
coupling of III˚ degree
{ ( π 1 ± ⊗ π 2 ± ) i ⊕ [ ( π 1 ± ⊗ π 2 ± ) j ⊕ ( π 1 ± ⊗ π 2 ± ) k ⊕ ( π 1 ± ⊗ π 2 ± ) r ] }
coupling of IV˚ degree