Math Is Fun Forum

coffeeking

Member

Registered: 2007-11-18

Posts: 44

Help in mathematical symbol...

Hi, I am an undergraduate currently taking a course in Complex Analysis. As my foundation in Sets Theory is not strong, I have problem understanding some of the expression used.

Below is a statement about countable compactness in Complex Analysis:

"A family F of subsets of C is said to cover S if

...

My question is, what does the expression

means?

From what I have learn, I read it as "S is a subset of the union of the set U which is an element of F" which sound confusing as we always use "

" to denote union of two things but now it's used to denote an union of something which is an element of something.

I will appreciate if anyone could explain it to me in the most layman term where possible.

Thanks in advance.

Last edited by coffeeking (2009-02-06 21:19:52)

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Help in mathematical symbol...

is a set of sets. The elements of

are sets. Hence it makes sense to talk about the union of elements of

.

coffeeking

Member

Registered: 2007-11-18

Posts: 44

Re: Help in mathematical symbol...

Hi Jane, I think you have hit the nail on the head and I have finally understood what it means.

Thanks