I am working through Bert Mendelson's "Introduction to Topology" and am having some trouble with proofs.
The text in well presented but to get a proper understanding I am working through the excercises. I am still on Chapter 1 which deals with sets and for the most part the excercises seem trivial to the point where its seems to me no proof is needed BUT there are a couple of questions that have me stumped (there are no worked solutions a problem with most maths books I find).
I would really apreciate it if somebody could walk me through a few proofs (it will probably take more than a couple before I get my head into gear), so here a couple of the excercises..
First one that seems trivial to me but one I am having trouble forming a proof for,
Secondly not so trivial to my mind,
Let be an indexed family of subsets of a set S. Let
Any help with this most apreciated.