Team Semantics for the Specification and Verification of Hyperproperties

TL;DR

This paper introduces team semantics for LTL to specify hyperproperties, analyzing its properties, complexity, and expressivity, and comparing it to HyperLTL as an alternative logic for hyperproperties.

Contribution

It develops a new team semantics framework for LTL tailored for hyperproperties, providing complexity analysis and expressivity comparison with HyperLTL.

Findings

Team semantics for LTL can express hyperproperties effectively.

The logic's satisfiability, path, and model checking problems are classified in terms of complexity.

LTL under team semantics offers a viable alternative to HyperLTL with better algorithmic properties.

Abstract

We develop team semantics for Linear Temporal Logic (LTL) to express hyperproperties, which have recently been identified as a key concept in the verification of information flow properties. Conceptually, we consider an asynchronous and a synchronous variant of team semantics. We study basic properties of this new logic and classify the computational complexity of its satisfiability, path, and model checking problem. Further, we examine how extensions of these basic logics react on adding other atomic operators. Finally, we compare its expressivity to the one of HyperLTL, another recently introduced logic for hyperproperties. Our results show that LTL under team semantics is a viable alternative to HyperLTL, which complements the expressivity of HyperLTL and has partially better algorithmic properties.