Comparing Trace Expressions and Linear Temporal Logic for Runtime Verification

Abstract

Trace expressions are a compact and expressive formalism, initially devised for runtime verification of agent interactions in multiagent systems, which has been successfully employed to model real protocols, and to generate monitors for mainstream multiagent system platforms, and generalized to support runtime verification of different kinds of properties and systems.In this paper we formally compare the expressive power of trace expressions with the Linear Temporal Logic (LTL), a formalism widely adopted in runtime verification. We show that any LTL formula can be translated into a trace expression which is equivalent from the point of view of runtime verification. Since trace expressions are able to express and verify sets of traces that are not context-free, we can derive that in the context of runtime verification trace expressions are more expressive than LTL.

A formalism for specification of Java API interfaces

“…Trace expressions [1] are a formalism expressly devised for runtime verification purposes [5]. In this context, the system under test is observed and relevant events are collected in a trace encoding the single execution.…”

Towards a framework for certification of reliable autonomous systems

“…There is not a sensor for every 'obvious' fault yet an autonomous system needs to account for all faults that are obvious to humans, even when they trigger fault warnings for unrelated errors. 8 There are three options to deal with a situation where a human is being replaced (partially or completely) with software, and the human interacts with an existing artefact using an interface. These options are: to retain the interface, and have the software interact with it; to extend the artefact with additional interfaces for the software; or to replace the artefact's interface completely.…”

“…-Inputs (1) Input data stream or streams containing time-stamped sensor or software values, e.g., sent over a system bus to the RV engine; (2) A requirement to verify, expressed in the form of a temporal logic formula, most commonly Mission-time Linear Temporal Logic (MLTL) [175,176,213] or First-Order Linear Temporal Logic (FOLTL) [20,76] whose variables are set by the input data or operationally via finite state automata, trace expressions [8], etc (see Sect. 2.1 of [83]).…”

Can determinism and compositionality coexist in RML?

“…The expressive power of LTL is the same as of star-free ω-regular languages [39]. When restricted to finite traces, RML is much more expressive than LTL as any regular expression can be trivially translated to it; however, on infinite traces, the comparison is slightly more intricate since RML and LTL 3 have incomparable expressiveness [8]. There exist many extensions of LTL that deal with time in a more quantitative way (as opposed to the strictly qualitative approach of standard LTL) without increasing the expressive power, like interval temporal logic [18], metric temporal logic [42] and timed LTL [15].…”