More like discrete math and automata theory https://en.m.wikipedia.org/wiki/Automata_theory https://en.m.wikipedia.org/wiki/Automata_theory or theory of computa

More like discrete math and automata theory https://en.m.wikipedia.org/wiki/Automata_theory https://en.m.wikipedia.org/wiki/Automata_theory or theory of computation. Hopcroft & Ullmann's intro book is nice. But there's so much related stuff here, it's just a starting point.