Abstract In this thesis, we present several theoretical and practical results on program verification, the main purpose being that of providing cost-efficient solutions to problems that almost always belong to undecidable classes. We appeal to logic and automata theory as they provide essentially the mechanisms to problem solving that are needed for program verification. In this respect, we investigate:

• logics for reasoning about infinite sets of program configurations, involving infinite data domains (array logics) and complex recursive data structures (separation logic), and
• automata extended with integer variables (counter machines), possibly with unbounded stacks (recursive integer programs).

We devoted special attention to the connection between logic and automata theory, by using counter machines and tree automata as effective decision procedures for array logics and separation logic, respectively. In this respect, we identified new decidable logical fragments and classes of automata and studied the complexity of their decision problems, such as, e.g. validity, reachability and termination, respectively. Most of these theoretical results have been implemented within prototype tools used to carry out experimental evaluations of their practical efficiency.