σ-Algebra

[Theo]

Ω:sample space
F:set
E:belongs

For an σ-algebra the following statments are true:
1)Ω E F
2)If A E F then Acomplement E F
3)the unions of Ai i={1,n} E F

Now i must prove that the intersections of Ai i={1,n} E F
with the De Morgans Law

Can you help me?

[matt grime]

complements swap union and intesection...