Problem 1. Let X=\ 0,1,2,3,4\ and mathcal A \ 0,X,\ 0\ ,\ 1,2,3,e\ \ a) Prove A is an algebra of subsets of X.
b) Is A a o-algebra of subsets of X?
c) Find an algebra D of subsets of X such that \ 0\ in mathcal D , mathcal D ne mathcal A and