Real and Complex analysis
- A collection of subsets of a set is said to be a -algebra in if has following properties:
- If , then , where is the complement of relative to .
- If and if for =1, 2, 3, ..., then .
- If is -algebra in , the is a measurable space. and the members of are called the measurable sets in .
- If is a measurable space, is topological space, and , the is said to be measurable provided that is a measurable set in for every open set in .