I've just noticed an assumption I've made in Who's good with proofs. I have assumed that


if a*b = 0 then either a is 0 or b is 0.

this is true for real and complex numbers, but not for all numbers, (it's not true for 2x2 matricies for example)

Code:
(1  0) (0  0)  = 0
(0  0) (0  1)

I think it holds true if multiplication is commutitive, but I'm not sure, does anyone know?


Again a proof or counterexample would be a great help (actually a counterexample would be a real arse but still)

Thanks.