Then, one can verify that both S and L satisfy the canonical angular momentum commutation relations [ S i , S j ] = i ℏ ℏ ϵ ϵ i j k S k , [ L i , L j ] = i ℏ ℏ ϵ ϵ i j k L k , and they commute with each other [ S i , L j ] = 0 .