@conference {778, title = {{\textquotedblleft}Talking{\textquotedblright} Triples to Museum Chatbots}, booktitle = {Proceedings of the 22nd International Conference on Human-Computer Interaction, volume "Culture and Computing"}, year = {2020}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

The paper presents recent work on the design and development of AI chatbots for museums using Knowledge Graphs (KGs). The utilization of KGs as a key technology for implementing chatbots raises not only issues related to the representation and structuring of exhibits{\textquoteright} knowledge in suitable formalism and models, but also issues related to the translation of natural language dialogues to and from the selected technology for the formal representation and structuring of information and knowledge. Moreover, such a translation must be as transparent as possible to visitors, towards a realistic human-like question-answering process. The paper reviews and evaluates a number of recent approaches for the use of KGs in developing AI chatbots, as well as key tools that provide solutions for natural language translation and the querying of Knowledge Bases and Linked Open Data sources. This evaluation aims to provide answers to issues that are identified within the proposed MuBot approach for designing and implementing AI chatbots for museums. The paper also presents Cretan MuBot, the first experimental KG/Ontology-based AI chatbot of the MuBot Platform, which is under development in the Heracleum Archaeological Museum.

}, keywords = {chatbots, knowledge graphs, Museums, NLP, RDF triples}, doi = {10.1007/978-3-030-50267-6_22}, author = {Savvas Varitimiadis and Konstantinos Kotis and Dimitris Spiliotopoulos and Costas Vassilakis and Dionisis Margaris} } @conference {783, title = {Threat landscape for smart grid systems}, booktitle = {Proceedings of the 15th International Conference on Availability, Reliability and Security}, year = {2020}, month = {jul}, publisher = {ACM}, organization = {ACM}, abstract = {

Smart Grids are energy delivery networks, constituting an evolution of power grids, in which a bidirectional flow between power providers and consumers is established. These flows support the transfer of electricity and information, in order to support automation actions in the context of the energy delivery network. Insofar, many smart grid implementations and implementation proposals have emerged, with varying degrees of feature delivery and sophistication. While smart grids offer many advantages, their distributed nature and information flow streams between energy producers and consumers enable the launching of a number of attacks against the smart grid infrastructure, where the related consequences may range from economic loss to complete failure of the smart grid. In this paper, we survey the threat landscape of smart grids, identifying threats that are specific to this infrastructure, providing an assessment of the severity of the consequences of each attack type, discerning features that can be utilized to detect attacks and listing methods that can be used to mitigate them.

}, keywords = {attack detection features, attack mitigation, attacks, security, Smart grids}, doi = {https://doi.org/10.1145/3407023.3409229}, author = {Christos-Minas Mathas and Konstantinos-Panagiotis Grammatikakis and Costas Vassilakis and Nicholas Kolokotronis and Vasiliki-Georgia Bilali and Dimitris Kavallieros} } @conference {789, title = {A Trust Management System for the IoT domain}, booktitle = {Proceedings the 2020 IEEE World Congress on Services (SERVICES)}, year = {2020}, publisher = {IEEE}, organization = {IEEE}, abstract = {

In modern internet-scale computing, interaction between a large number of parties that are not known a-priori is predominant, with each party functioning both as a provider and consumer of services and information. In such an environment, traditional access control mechanisms face considerable limitations, since granting appropriate authorizations to each distinct party is infeasible both due to the high number of grantees and the dynamic nature of interactions. Trust management has emerged as a solution to this issue, offering aids towards the automated verification of actions against security policies. In this paper, we present a trust- and risk-based approach to security, which considers status, behavior and associated risk aspects in the trust computation process, while additionally it captures user-to-user trust relationships which are propagated to the device level, through user-to-device ownership links.

}, keywords = {associated risk, behavior, Internet-of-things, status, trust management}, doi = {10.1109/SERVICES48979.2020.00047}, author = {Christos-Minas Mathas and Costas Vassilakis and Nicholas Kolokotronis} } @conference {724, title = {TripMentor: Challenges and prospects for culture and tourism in the Attica region (Greek title: {\textquotedblleft}TripMentor: προκλήσεις και προοπτικές για τον πολιτισμό και τον τουρισμό στην περιφέρεια Αττικής{\textquotedblleft})}, booktitle = {Proceedings of the 3nd Pan-Hellenic Conference on Digital Cultural Heritage-EuroMed 2019}, year = {2019}, abstract = {This paper presents the TripMentor project which is related to the tourism and civilization in the region of Attica. The main goal of the project is the presentation, in two languages, of the rich cultural content of the region to the tourists, through an Internet-based environment and through mobile applications. The goal of the project is to guide the visitors through many possible alternative routes, which include points of interest, as well as enterprises with tourism-related offers, while at the same time attempts to combine these routes with cultural points of interest. The project interrelates information, venues and visitor profiles with an automated way, striving to offer a unique personalized experience, tailored to the needs and preferences of each user. The project challenges are mainly technical, since through the project procedures (a) information regarding the points of interest should be gathered in an automated fashion (b) information about events related to points of interest must be taken into account and (v) data related to users, and especially the user profiles must be discovered and exploited so that the available information can be synthesized into a unique experience. In this context, we present the project application domain and the related challenges.}, keywords = {cultural information, culture, geospatial data, Social Networks, tourism, visitor profile}, author = {Costas Vassilakis and Vassilis Poulopoulos and Manolis Wallace and Angeliki Antoniou and George Lepouras} } @conference {713, title = {TripMentor Project: scope and challenges}, booktitle = {Proceedings of the Workshop on Cultural Informatics, co-located with the 14th International Workshop On Semantic And Social Media Adaptation And Personalization (SMAP 2019)}, year = {2019}, abstract = {We present Tripmentor, a novel project, that is related to tourism in the region of Attica. The project has as main scope to provide rich media content to tourists through a web and mobile environment in two languages trying to guide them through alternative routes that include places of interest as well as organizations with offers to tourists. The project interconnects people with places and events in an automated manner trying to personalize on each tourist{\textquoteright}s personality. The challenges of the project are mainly technological as through the processes of the project a) automated information about venues must be collected, b) information about events related to venues must be fetched and finally c) data related to system users and mainly their profile should be discovered and created in order to offer a unique experience to each of them. We present the scope of the project as well as the challenges of its implementation.}, keywords = {cultural related information, geodata, personalization, social media, tourism, tripmentor}, url = {http://ceur-ws.org/Vol-2412/paper6.pdf}, author = {Costas Vassilakis and Vassilis Poulopoulos and Manolis Wallace and Angeliki Antoniou and George Lepouras}, editor = {Angeliki Antoniou and Manolis Wallace} } @conference {lep14a, title = {Towards a Learning Analytics Platform for Supporting the Educational Process}, booktitle = {Proceedings of the 5th Conference on Information, Intelligence, Systems \& Application (IISA2014)}, year = {2014}, month = {7}, abstract = {In this paper, we present the vision of an open source learning analytics platform, able to harvest data from different sources, including e-learning platforms and environments, registrar{\textquoteright}s information systems, alumni systems, etc., so as to provide all stakeholders with the necessary functionality to make decisions on the learning process. The platform{\textquoteright}s architecture is modular, allowing the introduction of new functionality or connection to new systems to collect needed data. All data can be analyzed and presented though interactive visualizations to find correlations between metrics, to make predictions for students or student groups, to identify best practices for instructors and let them explore {\textquoteright}what-if{\textquoteright} scenarios, to offer students personalized recommendations and personalized detailed feedback, etc. Our objective is to inform and empower all stakeholders to improve the learning experience.}, doi = {10.1109/IISA.2014.6878750}, url = {http://ieeexplore.ieee.org/document/6878750/}, author = {Giorgos Lepouras and Akrivi Katifori and Costas Vassilakis and Angela Antoniou and Nikos Platis} } @article {antoniou11, title = {Towards a methodological framework for the cognitive-behavioural evaluation of educational e-games}, journal = {International Journal of Learning Technology}, volume = {6}, number = {3}, year = {2011}, pages = {263{\textendash}287}, abstract = {The proposed methodological framework reviews and uses knowledge from the field of cognitive psychology in order to evaluate aspects of educational games. In particular, we concentrate on two components of human cognition that play a central role to learning, namely memory and motivation. After having reviewed theories in the field, we created a questionnaire in order to evaluate educational games. The questionnaire incorporates different experimental findings of cognitive psychology. Especially, we have applied Maslow{\textquoteright}s motivation theory, Behavioural findings on reinforcement, experimental findings about attention and memory. We present the results obtained from the evaluation of two games, PAC-MAN and Mega Jump. The results confirmed the user ratings of the two games, showing that there seem to be cognitive reasons for the success/failure of different games. Finally, lists of guidelines for developers and instructors are included.}, doi = {10.1504/11.43580}, author = {Angela Antoniou and Dimitris Diakakis and Giorgos Lepouras and Costas Vassilakis} } @conference {kalikakis2007a, title = {Towards a P2P world: peered taxation}, booktitle = {Proceedings of the 2nd International Workshop "E-taxation: State \& Perspectives"}, year = {2007}, month = {2}, abstract = {This paper presents the current model for taxation and distribution of the taxes to government activities, and an alternative model is presented, according to which tax-payers can determine, to some extent, the way that the taxes they pay will be spent. The goal of this proposal is to increase citizen involvment and system transparency. The model proposal comescomplete with an architecture that supports the realization of the proposed scheme}, author = {M. Kalikakis and D. Gouscos and Costas Vassilakis and P. Georgiadis} } @conference {kareliotis2006, title = {Towards Dynamic, Relevance-Driven Exception Resolution in Composite Web Services}, booktitle = {Proceedings of OOPSLA 2006, Fourth International Workshop on SOA \& Web Services Best Practices}, year = {2006}, month = {10}, abstract = {Web services have become the leading technology for application-toapplication (A2A) communication over distributed and heterogeneous environments. Both academia and industry have strived to enable useful service collaborations among distributed systems without any human intervention. Web service composition can be used to this end, to achieve business automation within one company or realize business-to-business (B2B) integration of heterogeneous software and cross-organizational computing systems. Service composition pro-vides added value, when a web service composition itself becomes a higher level composite web service. However, as business processes are long-lasting transactions, exceptions may often occur, necessitating the replacement of a service component which has been made unavailable, hindering the completion of some business process. In this paper we present an exception resolving approach based on discovering replacement components that are functionally equivalent, taking also into account criteria for qualitative substitutability. The proposed solution introduces the Service Relevance and Replacement Framework (SRRF) which undertakes exception handling.}, author = {Christos Kareliotis and Costas Vassilakis and P. Georgiadis} } @conference {Lepouras_tailorabilityin, title = {Tailorability in the context of E-government Information Systems: An approach}, booktitle = {Proceedings of the IRMA 2004 conference}, year = {2004}, month = {5}, abstract = {The ever changing environment information systems model, and in particular e-government ones, intensifies the need for systems that are able to easily, efficiently and transparently adapt to changing environments. Accommodating unanticipated changes implies that systems must be able to adapt to changes occurring in and evolve in step with their changing environment. Adaptation is concerned with monitoring, analysing and understanding the patterns of the user{\textquoteright}s interaction with the system. Similarly, an information system is said to be evolutionary if it can be purposefully used in a dynamic environment. E-government information systems, in virtue of their nature and function, are driven by the need to adapt and evolve. This suggests that the design and implementation of such systems must provide the necessary infrastructure for evolution and adaptability. In other words, e-government information systems must abide to the Tailorable Information Systems paradigm. In this work we present a case study for the development of a Tailorable e-government information system.}, author = {Giorgos Lepouras and Anya Sotiropoulou and Dimitrios Theotokis and Costas Vassilakis} } @conference {650426, title = {Transactional e-Government Services: An Integrated Approach}, booktitle = {EGOV {\textquoteright}02: Proceedings of the First International Conference on Electronic Government}, year = {2002}, month = {9}, pages = {276{\textendash}279}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {London, UK}, abstract = {Although form-based transactional services are fundamental to electronic government activities, their widespread does neither meet the citizen{\textquoteright}s expectations, nor the potential offered by state-of-the-art technologies. Besides any bureaucratic impediments, the primary reason for this is that traditional software engineering approaches cannot satisfactorily handle all the aspects of electronic services lifecycle. In this paper we present experiences from developing and maintaining a set of electronic services for the Greek Ministry of Finance, and propose a new approach for handling electronic service projects. The proposed approach has been successfully employed for developing extensions to the existing services, as well as some new ones.}, isbn = {3-540-44121-2}, doi = {10.1007/978-3-540-46138-8_44}, url = {http://link.springer.com/chapter/10.1007\%2F978-3-540-46138-8_44}, author = {Costas Vassilakis and Laskaridis, G. and Giorgos Lepouras and S. Rouvas and P. Georgiadis} } @conference {DBLP:conf/iadt/SotiropoulouSV98, title = {Temporal Extension to ODMG}, booktitle = {IADT}, year = {1998}, month = {7}, pages = {304-311}, abstract = {In the past years a number of temporal extensions to the different database models have been proposed. Extensions to the relational model have been following the different SQL standards, while no attempts have been made to extend the OO-databases{\textquoteright} standard, defined by ODMG. In this paper we present a temporal extension to the ODMG standard, as this has been specified in the TOOBIS project. A Temporal Object Data Model, a Temporal Object Definition Language and a Temporal Object Query Language have been specified and have been proposed as extensions to the ODM, ODL and OQL of ODMG. This extension has been implemented over a commercial OODBMS, reinforcing and validating the effort of standardisation and portability of this extension.}, author = {Anya Sotiropoulou and Michael Souillard and Costas Vassilakis} } @conference {DBLP:conf/inforsid/SouillardVS98, title = {TOOBIS: Application de la gestion de donn{\'e}es temporelles dans le domaine de la recherche clinique}, booktitle = {INFORSID}, year = {1998}, month = {5}, pages = {147-165}, abstract = {Les donn?es temporelles, c{\textquoteright}est-?-dire des donn?es ?voluant dans le temps et pour lesquelles il est int?ressant de maintenir un historique des valeurs, ne sont pas utilis?es dans l{\textquoteright}industrie. Mais cela ne veut pas dire pour autant que les diverses applications existantes ne g?rent que des donn?es non temporelles. En fait, des donn?es temporelles doivent ?tre g?r?es par un grand nombre d{\textquoteright}applications et de secteurs industriels tels que la finance, l{\textquoteright}assurance, le suivi m?dical, les services de r?servation, etc. Ces applications utilisent le plus souvent le r?sultat de d?veloppements internes simulant des donn?es temporelles, qui peuvent ?tre co?teux. Le march? des solutions pour manipuler des donn?es temporelles est encore limit?, et ne r?pond pas ? tous les besoins. Cet article pr?sente les r?sultats du projet europ?en TOOBIS - Temporal Object Oriented dataBase within Information System - en mettant l{\textquoteright}accent sur une application g?rant des donn?es temporelles, d?velopp?e dans le domaine de la Recherche Clinique. TOOBIS propose une extension du standard des bases de donn?es orient?es objet afin de fournir un syst?me de gestion des bases de donn?es temporelles complet, ainsi qu{\textquoteright}une m?thodologie de conception temporelle.}, author = {Michael Souillard and Costas Vassilakis and Anya Sotiropoulou} } @conference {719700, title = {Transaction Support in a Temporal DBMS}, booktitle = {Proceedings of the International Workshop on Temporal Databases}, year = {1995}, month = {9}, pages = {255{\textendash}271}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {London, UK}, abstract = {Transactions are a significant concept in database systems, facilitating functions both at user and system level. However transaction support in temporal DBMSs has not yet received enough research attention. In this paper, we present techniques for incorporating transaction support in a temporal DBMS, which is implemented as an additional layer to a commercial RDBMS. These techniques overcome certain limitations imposed by the underlying RDBMS, and avoid excessive increment of the log size.}, isbn = {3-540-19945-4}, doi = {10.1007/978-1-4471-3033-8_14}, url = {http://link.springer.com/chapter/10.1007\%2F978-1-4471-3033-8_14}, author = {Costas Vassilakis and N. Lorentzos and P. Georgiadis} }