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Alexander Artikis

Bio: Alexander Artikis is an academic researcher from University of Piraeus. The author has contributed to research in topics: Event calculus & Complex event processing. The author has an hindex of 35, co-authored 158 publications receiving 3217 citations. Previous affiliations of Alexander Artikis include Imperial College London & Barcelona Supercomputing Center.


Papers
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Journal ArticleDOI
TL;DR: This article presents a theoretical and computational framework being developed for the executable specification of open agent societies, and demonstrates how the framework can be applied to specifying and executing a contract-net protocol.
Abstract: Electronic markets, dispute resolution and negotiation protocols are three types of application domains that can be viewed as open agent societies. Key characteristics of such societies are agent heterogeneity, conflicting individual goals and unpredictable behavior. Members of such societies may fail to, or even choose not to, conform to the norms governing their interactions. It has been argued that systems of this type should have a formal, declarative, verifiable, and meaningful semantics. We present a theoretical and computational framework being developed for the executable specification of open agent societies. We adopt an external perspective and view societies as instances of normative systems. In this article, we demonstrate how the framework can be applied to specifying and executing a contract-net protocol. The specification is formalized in two action languages, the C+ language and the Event Calculus, and executed using respective software implementations, the Causal Calculator and the Society Visualizer. We evaluate our executable specification in the light of the presented case study, discussing the strengths and weaknesses of the employed action languages for the specification of open agent societies.

228 citations

Proceedings ArticleDOI
15 Jul 2002
TL;DR: This work identifies the key concepts and illustrates how they are used by formalising an example employing the contract net protocol, and presents a formal framework for specifying, animating, and ultimately reasoning about and verifying the properties of open computational systems.
Abstract: E-markets and negotiation protocols are two types of application domains that can be viewed as open computational societies. Key characteristics of such societies are agent heterogeneity, conflicting individual goals and limited trust. The risk that members of such societies will not conform to specifications imposes the need for a framework that will facilitate the designers to determine to what extent it is desirable to deploy their agents in such societies. We address this need by presenting a formal framework for specifying, animating, and ultimately reasoning about and verifying the properties of open computational systems. We view computational systems from an external perspective, aiming to account for the institutional and social aspects of these systems. We identify the key concepts and illustrate how they are used by formalising an example employing the contract net protocol. The framework and associated logical inferences have been implemented as a software platform that provides automated animation of the global states of an open system (society) during its execution. Simulations have demonstrated that the implementation of the framework establishes a foundation for a rich, formal representation of open computational societies.

142 citations

Journal ArticleDOI
TL;DR: The evaluation shows that RTEC can support real-time event recognition and is capable of meeting the performance requirements identified in a survey of event processing use cases.
Abstract: Systems for symbolic event recognition accept as input a stream of time-stamped events from sensors and other computational devices, and seek to identify high-level composite events, collections of events that satisfy some pattern. RTEC is an Event Calculus dialect with novel implementation and ‘windowing’ techniques that allow for efficient event recognition, scalable to large data streams. RTEC supports the expression of rather complex events, such as ‘two people are fighting’, using simple primitives. It can operate in the absence of filtering modules, as it is only slightly affected by data that are irrelevant to the events we want to recognise. Furthermore, RTEC can deal with applications where event data arrive with a (variable) delay from, and are revised by, the underlying sources. RTEC can update already recognised events and recognise new events when data arrive with a delay or following data revision. We evaluate RTEC both theoretically, presenting a complexity analysis, and experimentally, using two real-world applications. The evaluation shows that RTEC can support real-time event recognition and is capable of meeting the performance requirements identified in a survey of event processing use cases.

108 citations

Proceedings Article
01 Jan 2014
TL;DR: This work presents a system for heterogeneous stream processing and crowdsourcing supporting intelligent urban trac management and demonstrates the system with a real-world use-case from Dublin city, Ireland.
Abstract: Urban trac gathers increasing interest as cities become bigger, crowded and \smart". We present a system for heterogeneous stream processing and crowdsourcing supporting intelligent urban trac management. Complex events related to trac congestion (trends) are detected from heterogeneous sources involving xed sensors mounted on intersections and mobile sensors mounted on public transport vehicles. To deal with data veracity, a crowdsourcing component handles and resolves sensor disagreement. Furthermore, to deal with data sparsity, a trac modelling component oers information in areas with low sensor coverage. We demonstrate the system with a real-world use-case from Dublin city, Ireland.

102 citations

Journal ArticleDOI
TL;DR: Extensive tests validate the performance, efficiency, and robustness of the system against scalable volumes of real-world and synthetically enlarged datasets, but its deployment against online feeds from vessels has also confirmed its capabilities for effective, real-time maritime surveillance.
Abstract: We present a system for online monitoring of maritime activity over streaming positions from numerous vessels sailing at sea. It employs an online tracking module for detecting important changes in the evolving trajectory of each vessel across time, and thus can incrementally retain concise, yet reliable summaries of its recent movement. In addition, thanks to its complex event recognition module, this system can also offer instant notification to marine authorities regarding emergency situations, such as risk of collisions, suspicious moves in protected zones, or package picking at open sea. Not only did our extensive tests validate the performance, efficiency, and robustness of the system against scalable volumes of real-world and synthetically enlarged datasets, but its deployment against online feeds from vessels has also confirmed its capabilities for effective, real-time maritime surveillance.

87 citations


Cited by
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01 Jan 2009

7,241 citations

Book Chapter
01 Jan 2010

1,556 citations

Journal ArticleDOI

1,083 citations

Journal ArticleDOI
TL;DR: A number of foundational contributions provided the basis for the formulation of argumentation models and their promotion in AI related settings and then a number of new themes that have emerged in recent years are considered, many of which provide the principal topics of the research presented in this volume.

1,002 citations