Originally Posted by

**powderteacher** Hello,

I am currently making my way through the preliminaries of my Intro to Analysis book and I need clarification on a few things. I am confused on how we can used the indexed family of sets notation to describe DeMorgan's Laws. How can I write with mathtype on these posts? Anyways my question is how can i use demorgans laws to write a simpler description of:

R\(the intersection from n=1 to inf of the indexed family of sets defined by

(-1/n,1/n)? Any help would be much appreciated, thanks