If we have a system of two electrons, addition of angular momentum tells us that the spin states of the composite system can be decomposed into those of the two electrons as follows
|1,1>=|+>|+>
|1,0>=(|+>|-> + |->|+>)√2
|1,-1>=|->|->
|0,0>=(|+>|-> - |->|+>)√2
where the states are |s,ms> for the...