Im reading Adel Bidal Introduction to SUSY. It is all pretty much clearly deduced from the asumptions, but I dont understand the asumptions... In particular, Im talking about the Qs commutation: 1 with Ps: why are they assumed to be 0. 2 with Ms: why are the proportional of Qs but not of Ms? 3 the sigmas: I sort of see why are the sigma mattrixes in the commutation relations but I cannot put it in words, so I will ask it anyway... Why are the sigmas there and not another mattrices? Thanks in advance and sorry for my english!