Then you should consult this great book, usually this kind of publications suffer from extreme theoretical approaches. This one is a very nice example of clean and tidy writing for beginners and advanced people who want to dive in the interesting wolrd of mathematical logic and discrete mathematics. Two thumbs up to the writer ! P.S. A colleague of mine told me that this is a good book for the course we are attending at Greek Open University. So I've read it in a university library and then decided to purchase it.