Books on mathematical Logic

[C0nfused]

Hi everybody,
I am looking for books about Logic and Set Theory. In particular, I am looking for not very advanced books. What are axioms, how do theorems connect to the axioms, how are we sure that some methods of proving give always correct and general results-these are some of the questions that I am looking for answers (i think this is part of mathematical logic, isn't it?). Any help would be appreciated
Thanks

P.S: I don't live in the U.S.A or U.K. so as you understand, only really well-known books might be found in my country. So I would prefer you to suggest some of the "classics" that can probably be found everywhere

[ramollari]

"Discrete Mathematics" from Kenneth Rosen, McGraw Hill, is a classic. It treats logic (along with other topics like number theory, sets, probability, Boolean Algebra, algorithms, etc) in depth, in clear language for beginners, with plenty of examples, exercises and case studies, many of which are drawn from computer science.

[C0nfused]

Thanks for your suggestion. I will check it out

[Tom Mattson]

A really great modern introduction to the subject is Language, Proof and Logic by Jon Barwise and John Etchemendy. Not only is the text superb, but it comes with software by which you can formulate arguments. And then you can send your solutions to their website's "Grade Grinder", and they will evaluate them for you!

The homepage (at Stanford) is here:

http://www-csli.stanford.edu/LPL/

Do check it out!