I got interested in formal language theory and would like to suplement my education.

Can you recommend me any good books on the topic?

Topics I am interested in are roughly these:

- foundations and fundmental theorems ( far reaching consequences of fundamental theorems are always awesome)
- grammar induction, whether it's even used anywhere and what are its limitations
- relationship to other fields and applications
- relationship to machine learning methods

Thanks!
Boosts welcome.