Mind the Gap: Addressing Behavioural Inconsistencies with Formal Methods

Abstract

Abstract-In complex system design, it is important to construct several design models focusing on different aspects of a system to gain a better understanding of individual component structure and behaviour. Scenarios of execution are commonly used to specify partial behaviour and interactions between a group of system objects or components. However, partial specifications may hide inconsistencies or an otherwise unintentionally incomplete or underspecified behavioural model. This paper proposes a new powerful technique combining constraint solvers and theorem provers to complete partial specifications and determine overall model inconsistencies. We use a trueconcurrent model, namely labelled event structures, which can be used as the underlying semantics of widely used workflow or scenario-based languages. We show how an interplay between the theorem prover Isabelle and constraint solver Z3 can be used for detecting and solving partial specifications and inconsistencies over event structures.

Formal Verification of CNL Health Recommendations

“…Another possible direction to guarantee the scalability of our approach, consists of exploring links to constraint solvers such as Z3 (for cases of bounded model checking). We have used constraint solvers considerably in our work, including our recent work in [5,7].…”

“…This work is part of a more general aim to integrate formal techniques, such as model checkers and constraint solvers, to detect and resolve inconsistencies in health recommendations and clinical guidelines. This paper adds a NLP dimension to our previous work on detecting inconsistencies in treatments for patients with multimorbidities [5], and the use of theorem provers and constraint solvers to detecting inconsistencies in requirements and scenarios of execution [6,7]. This paper is structured as follows: we describe existing related work in Section 2, and the problem we are addressing with our proposed framework in Section 3.…”

An integrated framework for verifying multiple care pathways

“…4) with two diverging exclusive gateways (E1 and E3) executed in parallel. The algorithm proceeds by first unfolding one of them (say E1), 3 thereby duplicating all the nodes following its corresponding converging gateway (E2). Since the causality relation is transitive, this duplication must be followed by a duplication also of the edges heading into all the nodes following the converging node (P2) corresponding to P1, since P2 has an incoming edge from E2.…”

“…Moreover, such formal specification can be used for further computations regarding the composition of several CPs. See [3] for further details. We also use Isabelle and SMT solvers to detect inconsistencies in the LESs generated automatically from two or more (single disease) BPMN models and propose resolutions.…”

Correct Composition of Dephased Behavioural Models

“…The Alloy analyzer is SAT solver-based and SAT-solving time may increase enormously, depending on factors such as the number of variables and the average length of the clause [9]. Z3 [16] performs much better and we have used it in more recent work [7,13,8]. We do not know of other approaches using Z3 for model composition.…”