🤖 AI Summary
This study investigates the evolution of truth values of Computation Tree Logic (CTL) properties during abstraction refinement. To this end, it systematically introduces modal logic into the abstraction refinement framework for the first time, enriching the semantics with two new modal operators: ◇ (indicating that some refinement satisfies a property) and □ (indicating that all refinements satisfy it), thereby capturing the notions of possibility and necessity in refinement. Building on control statements, the work proposes a general technique for proving upper bounds and establishes tight upper and lower bounds for modal CTL across three canonical settings—finite abstractions, the full abstraction lattice, and complete transition systems—providing both a theoretical foundation and analytical tools for reasoning about property preservation across abstraction levels in formal verification.
📝 Abstract
Iterative abstraction refinement techniques are one of the most prominent paradigms for the analysis and verification of systems with large or infinite state spaces. This paper investigates the changes of truth values of system properties expressible in computation tree logic (CTL) when abstractions of transition systems are refined. To this end, the paper utilizes modal logic by defining alethic modalities expressing possibility and necessity on top of CTL: The modal operator $\lozenge$ is interpreted as"there is a refinement, in which ..."and $\Box$ is interpreted as"in all refinements, ...". Upper and lower bounds for the resulting modal logics of abstraction refinement are provided for three scenarios: 1) when considering all finite abstractions of a transition system, 2) when considering all abstractions of a transition system, and 3) when considering the class of all transition systems. Furthermore, to prove these results, generic techniques to obtain upper bounds of modal logics using novel types of so-called control statements are developed.