561 research outputs found
CONCUR Test-Of-Time Award 2020 Announcement
This short article announces the recipients of the CONCUR Test-of-Time Award 2020
2-Nested Simulation is not Finitely Equationally Axiomatizable
2-nested simulation was introduced by Groote and Vaandrager [10] as the coarsest equivalence included in completed trace equivalence for which the tyft/tyxt format is a congruence format. In the lineartime-branching time spectrum of van Glabbeek [8], 2-nested simulationis one of the few equivalences for which no finite equational axiomatization is presented. In this paper we prove that such an axiomatizationdoes not exist for 2-nested simulation.Keywords: Concurrency, process algebra, basic CCS, 2-nested simulation, equational logic, complete axiomatizations
Concurrent constraint programming with process mobility
We propose an extension of concurrent constraint programming with primitives for process migration within a hierarchical network, and we study its semantics. To this purpose, we first investigate a "pure " paradigm for process migration, namely a paradigm where the only actions are those dealing with transmissions of processes. Our goal is to give a structural definition of the semantics of migration; namely, we want to describe the behaviour of the system, during the transmission of a process, in terms of the behaviour of the components. We achieve this goal by using a labeled transition system where the effects of sending a process, and requesting a process, are modeled by symmetric rules (similar to handshaking-rules for synchronous communication) between the two partner nodes in the network. Next, we extend our paradigm with the primitives of concurrent constraint programming, and we show how to enrich the semantics to cope with the notions of environment and constraint store. Finally, we show how the operational semantics can be used to define an interpreter for the basic calculus.
The Power of Proofs: New Algorithms for Timed Automata Model Checking (with Appendix)
This paper presents the first model-checking algorithm for an expressive
modal mu-calculus over timed automata, , and reports performance results for an implementation.
This mu-calculus contains extended time-modality operators and can express all
of TCTL. Our algorithmic approach uses an "on-the-fly" strategy based on proof
search as a means of ensuring high performance for both positive and negative
answers to model-checking questions. In particular, a set of proof rules for
solving model-checking problems are given and proved sound and complete; we
encode our algorithm in these proof rules and model-check a property by
constructing a proof (or showing none exists) using these rules. One noteworthy
aspect of our technique is that we show that verification performance can be
improved with \emph{derived rules}, whose correctness can be inferred from the
more primitive rules on which they are based. In this paper, we give the basic
proof rules underlying our method, describe derived proof rules to improve
performance, and compare our implementation of this model checker to the UPPAAL
tool.Comment: This is the preprint of the FORMATS 2014 paper, but this is the full
version, containing the Appendix. The final publication is published from
Springer, and is available at
http://link.springer.com/chapter/10.1007%2F978-3-319-10512-3_9 on the
Springer webpag
On Observability and Monitoring of Distributed Systems: An Industry Interview Study
Business success of companies heavily depends on the availability and
performance of their client applications. Due to modern development paradigms
such as DevOps and microservice architectural styles, applications are
decoupled into services with complex interactions and dependencies. Although
these paradigms enable individual development cycles with reduced delivery
times, they cause several challenges to manage the services in distributed
systems. One major challenge is to observe and monitor such distributed
systems. This paper provides a qualitative study to understand the challenges
and good practices in the field of observability and monitoring of distributed
systems. In 28 semi-structured interviews with software professionals we
discovered increasing complexity and dynamics in that field. Especially
observability becomes an essential prerequisite to ensure stable services and
further development of client applications. However, the participants mentioned
a discrepancy in the awareness regarding the importance of the topic, both from
the management as well as from the developer perspective. Besides technical
challenges, we identified a strong need for an organizational concept including
strategy, roles and responsibilities. Our results support practitioners in
developing and implementing systematic observability and monitoring for
distributed systems
A foundation for runtime monitoring
Runtime Verification is a lightweight technique that complements other verification methods in an effort to ensure software correctness. The technique poses novel questions to software engineers: it is not easy to identify which specifications are amenable to runtime monitor-ing, nor is it clear which monitors effect the required runtime analysis correctly. This exposition targets a foundational understanding of these questions. Particularly, it considers an expressive specification logic (a syntactic variant of the modal ÎĽ-calculus) that is agnostic of the verification method used, together with an elemental framework providing an operational semantics for the runtime analysis performed by monitors. The correspondence between the property satisfactions in the logic on the one hand, and the verdicts reached by the monitors performing the analysis on the other, is a central theme of the study. Such a correspondence underpins the concept of monitorability, used to identify the subsets of the logic that can be adequately monitored for by RV. Another theme of the study is that of understanding what should be expected of a monitor in order for the verification process to be correct. We show how the monitor framework considered can constitute a basis whereby various notions of monitor correctness may be defined and investigated.peer-reviewe
Harmonic analysis and hypercomplex function theory in co-dimension one
Fundamentals of a function theory in co-dimension one for Clifford algebra valued functions over â„ťn+1 are considered. Special attention is given to their origins in analytic properties of holomorphic functions of one and, by some duality reasons, also of several complex variables. Due to algebraic peculiarities caused by non-commutativity of the Clifford product, generalized holomorphic functions are characterized by two different but equivalent properties: on one side by local derivability (existence of a well defined derivative related to co-dimension one) and on the other side by differentiability (existence of a local approximation by linear mappings related to dimension one). As important applications, sequences of harmonic Appell polynomials are considered whose definition and explicit analytic representations rely essentially on both dual approaches.The work of the first, second and fourth authors was supported by Portuguese funds through the CIDMA - Center for Research and Development in Mathematics and Applications, and the Portuguese Foundation for
Science and Technology (“FCT-Fundação para a Ciência e Tecnologia”), within project PEst-OE/MAT/UI4106/2013. The work of the second author was supported by Portuguese funds through the CMAT - Centre of Mathematics and FCT within the Project UID/MAT/00013/2013
A Foundation for Runtime Monitoring
Runtime Verification is a lightweight technique that complements other
verification methods in an effort to ensure software correctness.
The technique poses novel questions to software engineers: it is not easy to
identify which specifications are amenable to runtime monitoring, nor is it
clear which monitors effect the required runtime analysis correctly.
This exposition targets a foundational understanding of these questions.
Particularly, it considers an expressive specification logic (a syntactic
variant of the mmucalc) that is agnostic of the verification method used,
together with an elemental framework providing an operational semantics for the
runtime analysis performed by monitors.
The correspondence between the property satisfactions in the logic on the one
hand, and the verdicts reached by the monitors performing the analysis on the
other, is a central theme of the study.
Such a correspondence underpins the concept of monitorability, used to identify
the subsets of the logic that can be adequately monitored for by RV.
Another theme of the study is that of understanding what should be expected of a
monitor in order for the verification process to be correct.
We show how the monitor framework considered can constitute a basis whereby
various notions of monitor correctness may be defined and investigated
CONCUR Test-of-time award 2020 announcement
This short article announces the recipients of the CONCUR Test-of-Time Award 2020
- …