Well, it's the same as just aboveA v A = U (or I think it might be A)
Just in case, A^A=A
See here : http://www.mathhelpforum.com/math-he...ns-proofs.htmlA ^ null set = A
A v null set = A
Make a diagram if you want to check by yourself !
uh ? just as beforeAnd finally if A is a subset of U,
null set v A = A
Yepcomplement of the null set = U
'welcome ^^Thanks for looking!