16,716 research outputs found
Propositional Dynamic Logic for Message-Passing Systems
We examine a bidirectional propositional dynamic logic (PDL) for finite and
infinite message sequence charts (MSCs) extending LTL and TLC-. By this kind of
multi-modal logic we can express properties both in the entire future and in
the past of an event. Path expressions strengthen the classical until operator
of temporal logic. For every formula defining an MSC language, we construct a
communicating finite-state machine (CFM) accepting the same language. The CFM
obtained has size exponential in the size of the formula. This synthesis
problem is solved in full generality, i.e., also for MSCs with unbounded
channels. The model checking problem for CFMs and HMSCs turns out to be in
PSPACE for existentially bounded MSCs. Finally, we show that, for PDL with
intersection, the semantics of a formula cannot be captured by a CFM anymore
An adequate logic for full LOTOS
We present a novel result for a logic for symbolic transition systems based on LOTOS processes. The logic is adequate with respect to bisimulation defined on symbolic transition systems
Verifying message-passing programs with dependent behavioural types
Concurrent and distributed programming is notoriously hard. Modern languages and toolkits ease this difficulty by offering message-passing abstractions, such as actors (e.g., Erlang, Akka, Orleans) or processes (e.g., Go): they allow for simpler reasoning w.r.t. shared-memory concurrency, but do not ensure that a program implements a given specification. To address this challenge, it would be desirable to specify and verify the intended behaviour of message-passing applications using types, and ensure that, if a program type-checks and compiles, then it will run and communicate as desired. We develop this idea in theory and practice. We formalise a concurrent functional language λπ ⩽, with a new blend of behavioural types (from π-calculus theory), and dependent function types (from the Dotty programming language, a.k.a. the future Scala 3). Our theory yields four main payoffs: (1) it verifies safety and liveness properties of programs via type– level model checking; (2) unlike previous work, it accurately verifies channel-passing (covering a typical pattern of actor programs) and higher-order interaction (i.e., sending/receiving mobile code); (3) it is directly embedded in Dotty, as a toolkit called Effpi, offering a simplified actor-based API; (4) it enables an efficient runtime system for Effpi, for highly concurrent programs with millions of processes/actors
An interval logic for higher-level temporal reasoning
Prior work explored temporal logics, based on classical modal logics, as a framework for specifying and reasoning about concurrent programs, distributed systems, and communications protocols, and reported on efforts using temporal reasoning primitives to express very high level abstract requirements that a program or system is to satisfy. Based on experience with those primitives, this report describes an Interval Logic that is more suitable for expressing such higher level temporal properties. The report provides a formal semantics for the Interval Logic, and several examples of its use. A description of decision procedures for the logic is also included
An Abstract Formal Basis for Digital Crowds
Crowdsourcing, together with its related approaches, has become very popular
in recent years. All crowdsourcing processes involve the participation of a
digital crowd, a large number of people that access a single Internet platform
or shared service. In this paper we explore the possibility of applying formal
methods, typically used for the verification of software and hardware systems,
in analysing the behaviour of a digital crowd. More precisely, we provide a
formal description language for specifying digital crowds. We represent digital
crowds in which the agents do not directly communicate with each other. We
further show how this specification can provide the basis for sophisticated
formal methods, in particular formal verification.Comment: 32 pages, 4 figure
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