Everything You Always Wanted to Know About Generalization of Proof Obligations in PDR

In this paper we revisit the topic of generalizing proof obligations in bit-level Property Directed Reachability (PDR). We provide a comprehensive study which (1) determines the complexity of the problem, (2) thoroughly analyzes limitations of existing methods, (3) introduces approaches to proof obligation generalization that have never been used in the context of PDR, (4) compares the strengths of different methods from a theoretical point of view, and (5) intensively evaluates the methods on various benchmarks from hardware model checking as well as from AI planning.