20,792 research outputs found
Model Checking Real-Time Conditional Commitment Logic using Transformation
A new logical language for real-time conditional commitments called RTCTLcc has been developed by extending the CTL logic with interval bounded until modalities, conditional commitment modalities, and fulfillment modalities. RTCTLcc allows us to express qualitative and quantitative commitment requirements in a convenient way. These requirements can be used to model multi-agent systems (MASs) employed in environments that react properly and timely to events occurring at time instants or within time intervals. However, the timing requirements and behaviors of MASs need an appropriate way to scale and bundle and should be carefully analyzed to ensure their correctness, especially when agents are autonomous. In this paper, we develop transformation algorithms that are fully implemented in a new Java toolkit for automatically transforming the problem of model checking RTCTLcc into the problem of model checking RTCTL (real-time CTL). The toolkit engine is built on top of the NuSMV tool, effectively used to automatically verify and analyze the correctness of real-time distributed systems. We analyzed the time and space computational complexity of the RTCTLcc model checking problem. We proved the soundness and completeness of the transformation technique and experimentally evaluated the validity of the toolkit using a set of business scenarios. Moreover, we added a capability in the toolkit to automatically scale MASs and to bundle requirements in a parametric form. We experimentally evaluated the scalability aspect of our approach using the standard ordering protocol. We further validated the approach using an industrial case study
Model Checking Trust-based Multi-Agent Systems
Trust has been the focus of many research projects, both theoretical and practical, in
the recent years, particularly in domains where open multi-agent technologies are applied
(e.g., Internet-based markets, Information retrieval, etc.). The importance of trust in such
domains arises mainly because it provides a social control that regulates the relationships
and interactions among agents. Despite the growing number of various multi-agent applications, they still encounter many challenges in their formal modeling and the verification
of agents’ behaviors. Many formalisms and approaches that facilitate the specifications of
trust in Multi-Agent Systems (MASs) can be found in the literature. However, most of these
approaches focus on the cognitive side of trust where the trusting entity is normally capable
of exhibiting properties about beliefs, desires, and intentions. Hence, the trust is considered
as a belief of an agent (the truster) involving ability and willingness of the trustee to perform some actions for the truster. Nevertheless, in open MASs, entities can join and leave
the interactions at any time. This means MASs will actually provide no guarantee about the
behavior of their agents, which makes the capability of reasoning about trust and checking
the existence of untrusted computations highly desired.
This thesis aims to address the problem of modeling and verifying at design time
trust in MASs by (1) considering a cognitive-independent view of trust where trust ingredients are seen from a non-epistemic angle, (2) introducing a logical language named Trust
Computation Tree Logic (TCTL), which extends CTL with preconditional, conditional, and graded trust operators along with a set of reasoning postulates in order to explore its capabilities, (3) proposing a new accessibility relation which is needed to define the semantics
of the trust modal operators. This accessibility relation is defined so that it captures the
intuition of trust while being easily computable, (4) investigating the most intuitive and
efficient algorithm for computing the trust set by developing, implementing, and experimenting different model checking techniques in order to compare between them in terms of
memory consumption, efficiency, and scalability with regard to the number of considered
agents, (5) evaluating the performance of the model checking techniques by analyzing the
time and space complexity.
The approach has been applied to different application domains to evaluate its computational performance and scalability. The obtained results reveal the effectiveness of the
proposed approach, making it a promising methodology in practice
PDDL2.1: An extension of PDDL for expressing temporal planning domains
In recent years research in the planning community has moved increasingly towards application of planners to realistic problems involving both time and many types of resources. For example, interest in planning demonstrated by the space research community has inspired work in observation scheduling, planetary rover ex ploration and spacecraft control domains. Other temporal and resource-intensive domains including logistics planning, plant control and manufacturing have also helped to focus the community on the modelling and reasoning issues that must be confronted to make planning technology meet the challenges of application. The International Planning Competitions have acted as an important motivating force behind the progress that has been made in planning since 1998. The third competition (held in 2002) set the planning community the challenge of handling time and numeric resources. This necessitated the development of a modelling language capable of expressing temporal and numeric properties of planning domains. In this paper we describe the language, PDDL2.1, that was used in the competition. We describe the syntax of the language, its formal semantics and the validation of concurrent plans. We observe that PDDL2.1 has considerable modelling power --- exceeding the capabilities of current planning technology --- and presents a number of important challenges to the research community
Institutionalising Ontology-Based Semantic Integration
We address what is still a scarcity of general mathematical foundations for ontology-based semantic integration underlying current knowledge engineering methodologies in decentralised and distributed environments. After recalling the first-order ontology-based approach to semantic integration and a formalisation of ontological commitment, we propose a general theory that uses a syntax-and interpretation-independent formulation of language, ontology, and ontological commitment in terms of institutions. We claim that our formalisation generalises the intuitive notion of ontology-based semantic integration while retaining its basic insight, and we apply it for eliciting and hence comparing various increasingly complex notions of semantic integration and ontological commitment based on differing understandings of semantics
Extended Representations of Observables and States for a Noncontextual Reinterpretation of QM
A crucial and problematical feature of quantum mechanics (QM) is
nonobjectivity of properties. The ESR model restores objectivity reinterpreting
quantum probabilities as conditional on detection and embodying the
mathematical formalism of QM into a broader noncontextual (hence local)
framework. We propose here an improved presentation of the ESR model containing
a more complete mathematical representation of the basic entities of the model.
We also extend the model to mixtures showing that the mathematical
representations of proper mixtures does not coincide with the mathematical
representation of mixtures provided by QM, while the representation of improper
mixtures does. This feature of the ESR model entails that some interpretative
problems raising in QM when dealing with mixtures are avoided. From an
empirical point of view the predictions of the ESR model depend on some
parameters which may be such that they are very close to the predictions of QM
in most cases. But the nonstandard representation of proper mixtures allows us
to propose the scheme of an experiment that could check whether the predictions
of QM or the predictions of the ESR model are correct.Comment: 17 pages, standard latex. Extensively revised versio
Symbolic Abstractions for Quantum Protocol Verification
Quantum protocols such as the BB84 Quantum Key Distribution protocol exchange
qubits to achieve information-theoretic security guarantees. Many variants
thereof were proposed, some of them being already deployed. Existing security
proofs in that field are mostly tedious, error-prone pen-and-paper proofs of
the core protocol only that rarely account for other crucial components such as
authentication. This calls for formal and automated verification techniques
that exhaustively explore all possible intruder behaviors and that scale well.
The symbolic approach offers rigorous, mathematical frameworks and automated
tools to analyze security protocols. Based on well-designed abstractions, it
has allowed for large-scale formal analyses of real-life protocols such as TLS
1.3 and mobile telephony protocols. Hence a natural question is: Can we use
this successful line of work to analyze quantum protocols? This paper proposes
a first positive answer and motivates further research on this unexplored path
A Survey of Symbolic Execution Techniques
Many security and software testing applications require checking whether
certain properties of a program hold for any possible usage scenario. For
instance, a tool for identifying software vulnerabilities may need to rule out
the existence of any backdoor to bypass a program's authentication. One
approach would be to test the program using different, possibly random inputs.
As the backdoor may only be hit for very specific program workloads, automated
exploration of the space of possible inputs is of the essence. Symbolic
execution provides an elegant solution to the problem, by systematically
exploring many possible execution paths at the same time without necessarily
requiring concrete inputs. Rather than taking on fully specified input values,
the technique abstractly represents them as symbols, resorting to constraint
solvers to construct actual instances that would cause property violations.
Symbolic execution has been incubated in dozens of tools developed over the
last four decades, leading to major practical breakthroughs in a number of
prominent software reliability applications. The goal of this survey is to
provide an overview of the main ideas, challenges, and solutions developed in
the area, distilling them for a broad audience.
The present survey has been accepted for publication at ACM Computing
Surveys. If you are considering citing this survey, we would appreciate if you
could use the following BibTeX entry: http://goo.gl/Hf5FvcComment: This is the authors pre-print copy. If you are considering citing
this survey, we would appreciate if you could use the following BibTeX entry:
http://goo.gl/Hf5Fv
Graphical modelling language for spycifying concurrency based on CSP
Introduced in this (shortened) paper is a graphical modelling language for specifying concurrency in software designs. The language notations are derived from CSP and the resulting designs form CSP diagrams. The notations reflect both data-flow and control-flow aspects of concurrent software architectures. These designs can automatically be described by CSP algebraic expressions that can be used for formal analysis. The designer does not have to be aware of the underlying mathematics. The techniques and rules presented provide guidance to the development of concurrent software architectures. One can detect and reason about compositional conflicts (errors in design), potential deadlocks (errors at run-time), and priority inversion problems (performance burden) at a high level of abstraction. The CSP diagram collaborates with objectoriented modelling languages and structured methods
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