I am studying mathematics at the undergraduate level and I am interested in the world of mathematical logic. I would like to know the opinion about which books or texts are recommended for an introduction to the subject and then a deepening?
I am grateful to all those people who give me their opinion or recommendation of texts or notes, on mathematical logic.
Try the Beginning Mathematical Logic Study Guide which is a cheap pbk and is also freely downloadable as a PDF. It has extensive suggestions at various levels across the different fields of mathematical logic.
The Guide is downloaded about 2K times a month, so I guess people are finding it useful.