@article {723,
	title = {A Fine-grained Social Network Recommender System},
	journal = {Social Network Analysis and Mining},
	volume = {10},
	year = {2020},
	abstract = {Recommender systems have greatly evolved in recent years and have become an integral part of the Web. From e-commerce sites to mobile apps, our daily routine revolves around a series of {\textquotedblleft}small{\textquotedblright} decisions that are influenced by such recommendations. In a similar manner, online social networks recommend only a subset of the massive amount of content published by a user{\textquoteright}s friends. However, the prevalent approach for the content selection process in such systems is driven by the amount of interaction between the user and the friend who published the content. As a result, content of interest is often lost due to weak social ties. In this paper, we present a fine-grained recommender system for social ecosystems, designed to recommend media content (e.g., music videos, online clips) published by the user{\textquoteright}s friends. The system design was driven by the findings of our qualitative user study that explored the value and requirements of a recommendation component within a social network. The core idea behind the proposed approach was to leverage the abundance of preexisting information in each user{\textquoteright}s account for creating interest profiles, to calculate similarity scores at a fine-grained level for each friend. The intuition behind the proposed method was to find consistent ways to obtain information representations that can identify overlapping interests in very specific sub-categories (e.g., two users{\textquoteright} music preferences may only coincide on hard rock). While the system is intended as a component of the social networking service, we developed a proof-of-concept implementation for Facebook and explored the effectiveness of our underlying mechanisms for content analysis. Our experimental evaluation demonstrates the effectiveness of our approach, as the recommended content of interest was both overlooked by the existing Facebook engine and not contained in the users{\textquoteright} Facebook News Feed. We also conducted a user study for exploring the usability aspects of the prototype and found that it offers functionality that could significantly improve user experience in popular services.},
	keywords = {Content Analysis, Interest Profiles, Recommender Systems, Social Networks, Usability},
	issn = {1869-5469},
	doi = {10.1007/s13278-019-0621-7},
	author = {Markos Aivazoglou and Antonios Roussos and Dionisis Margaris and Costas Vassilakis and Sotiris Ioannidis and Jason Polakis and Dimitris Spiliotopoulos}
}
@conference {795,
	title = {From Smart Cities to Smart Rural Country: challenges and sustainability},
	booktitle = {Extended abstract Presentation in the 15th National and International Conderence of the Hellenic Society for Systemic Studies},
	year = {2020},
	abstract = {<p>This work presents the current progress on smart cities initiatives, major breakthroughs and challenges. It also reviews the smart villages and smart rural environments as the next evolution of the smart cities vision. The purpose of the Smart Cities Mission is to drive economic growth and improve the quality of life of people by enabling local area development and harnessing technology, especially technology that leads to Smart outcomes. Technologies such as IoT (sensors, networks and applications) can be leveraged to improve city services, utilities, the environment and quality of life. All technologies have a common base, big data. Relevant data are collected by local sensors, such as citizens and local activities and global sensors, such as the environment, financial institutions and government sources. Data from disparate sources (traffic, air/water quality and usage, energy usage, resident movement) is constantly collected and is available for analysis The aim is to use the already gained expertise and insights from the smart cities approaches, applications and evaluations as well as the early works on smart villages and rural spaces to formulate the challenges and sustainability goals for the smart rural country. The findings of this work are mostly applied to medium- and long-term challenges as well as toward the notion of smart communities. Smart communities represent the notion of abstract connected objects within or spanning smart urban and rural spaces, such as smart cultural heritage, smart environment, and others. Introducing the non-technical goals for smart communities provides the sense of purpose and tangible targets for the technical-oriented smart urban and rural approaches, for aspiration and sustainability planning for the future.</p>
},
	author = {Dimitris Spiliotopoulos and Athanasios Kriemadis and Costas Vassilakis}
}
@conference {DBLP:conf/ssdbm/KaffesBSS18,
	title = {Finding shortest keyword covering routes in road networks},
	booktitle = {Proceedings of the 30th International Conference on Scientific and Statistical Database Management, SSDBM 2018, Bozen-Bolzano, Italy, July 09-11, 2018},
	year = {2018},
	pages = {12:1{\textendash}12:12},
	doi = {10.1145/3221269.3223038},
	url = {https://doi.org/10.1145/3221269.3223038},
	author = {Vassilis Kaffes and Alexandros Belesiotis and Dimitrios Skoutas and Spiros Skiadopoulos}
}
@article {DBLP:journals/jbd/Chatzigeorgakidis18,
	title = {FML-kNN: scalable machine learning on Big Data using \emphk-nearest neighbor joins},
	journal = {J. Big Data},
	volume = {5},
	year = {2018},
	pages = {4},
	doi = {10.1186/s40537-018-0115-x},
	url = {https://doi.org/10.1186/s40537-018-0115-x},
	author = {Georgios Chatzigeorgakidis and Sophia Karagiorgou and Spiros Athanasiou and Spiros Skiadopoulos}
}
@conference {bourlakos-ikc17,
	title = {Formalization and visualization of the narrative for museum guides},
	booktitle = {Proceedings of the third International KEYSTONE Conference (IKC2017)},
	year = {2017},
	month = {09},
	publisher = {Springer},
	organization = {Springer},
	abstract = {There is a wide range of meta-data standards for the documentation of museum related information, such as CIDOC-CRM; these standards focus on the description of distinct exhibits. In contrast, there is a lack of standards for the digitization and documentation of the routes followed and information provided by museum guides. In this work we propose the notion of the narrative, which can be used to model a guided museum visit. We provide a formalization for the narrative so that it can be digitally encoded, and thus preserved, shared, re-used, further developed and exploited, and also propose an intuitive visualization approach.},
	doi = {https://doi.org/10.1007/978-3-319-74497-1_1},
	url = {https://link.springer.com/chapter/10.1007/978-3-319-74497-1_1},
	author = {Ioannis Bourlakos and Manolis Wallace and Angela Antoniou and Costas Vassilakis and Giorgos Lepouras and Anna Vassiliki Karapanagiotou}
}
@conference {DBLP:conf/esws/ZervakisTSK16,
	title = {Full-Text Support for Publish/Subscribe Ontology Systems},
	booktitle = {The Semantic Web. Latest Advances and New Domains - 13th International Conference, ESWC 2016, Heraklion, Crete, Greece, May 29 - June 2, 2016, Proceedings},
	year = {2016},
	pages = {233{\textendash}249},
	doi = {10.1007/978-3-319-34129-3_15},
	url = {https://doi.org/10.1007/978-3-319-34129-3_15},
	author = {Lefteris Zervakis and Christos Tryfonopoulos and Spiros Skiadopoulos and Manolis Koubarakis}
}
@article {DBLP:journals/corr/ZervakisTPKS13,
	title = {Full-text Support for Publish/Subscribe Ontology Systems},
	journal = {CoRR},
	volume = {abs/1307.2015},
	year = {2013},
	url = {http://arxiv.org/abs/1307.2015},
	author = {Lefteris Zervakis and Christos Tryfonopoulos and Antonios Papadakis-Pesaresi and Manolis Koubarakis and Spiros Skiadopoulos}
}
@conference {554,
	title = {Full-text Support for Publish/Subscribe Ontology Systems},
	booktitle = {Proceedings of the Extended Semantic Web Conference (ESWC)},
	year = {2012},
	month = {May},
	address = {Crete, Greece},
	author = {Lefteris Zervakis and Christos Tryfonopoulos and Antonios Papadakis-Pesaresi and Manolis Koubarakis and Spiros Skiadopoulos}
}
@article {dix2010b,
	title = {From the web of data to a world of action},
	journal = {Journal of Web Semantics},
	volume = {8 issue 4},
	year = {2010},
	pages = {394-408},
	abstract = {This paper takes as its premise that the web is a place of action, not just information, and that the purpose of global data is to serve human needs. The paper presents several component technologies, which together work towards a vision where many small micro-applications can be threaded together using automated assistance to enable a unified and rich interaction. These technologies include data detector technology to enable any text to become a start point of semantic interaction; annotations for web-based services so that they can link data to potential actions; spreading activation over personal ontologies, to allow modelling of context; algorithms for automatically inferring {\textquoteleft}typing{\textquoteright} of web-form input data based on previous user inputs; and early work on inferring task structures from action traces. Some of these have already been integrated within an experimental web-based (extended) bookmarking tool, Snip!t, and a prototype desktop application On Time, and the paper discusses how the components could be more fully, yet more openly, linked in terms of both architecture and interaction. As well as contributing to the goal of an action and activity-focused web, the work also exposes a number of broader issues, theoretical, practical, social and economic, for the Semantic Web.},
	doi = {10.1016/j.websem.2010.04.007},
	author = {Alan Dix and Giorgos Lepouras and Akrivi Katifori and Costas Vassilakis and Tiziana Catarci and Antonella Poggi and Yannis Ioannidis and Miguel Morae and I. Daradimos and Nazihah Md.Akima and Shah Rukh Humayound and Fabio Terella}
}
@conference {vas2009d,
	title = {A framework for adaptation in secure web services},
	booktitle = {Proceedings of MCIS 2009},
	year = {2009},
	month = {9},
	abstract = {In the context of service-oriented computing, the introduction of the Quality-of-Service (QoS) aspect leads to the need to adapt the execution of programs to the QoS requirements of the particular execution. This is typically achieved by finding alternate services that are functionally equivalent to the ones originally specified in the program and whose QoS characteristics closely match the requirements, and invoking the alternate services instead of the originally specified ones; the same approach can also be employed for tackling exceptions. The techniques proposed insofar, however, cannot be applied in a secure context, where data are encrypted and signed for the originally intended recipient. In this paper, we introduce a framework for facilitating adaptation in the context of secure SOA.},
	author = {Costas Vassilakis and Christos Kareliotis}
}
@article {DBLP:journals/tkde/SkiadopoulosSSK07,
	title = {A Family of Directional Relation Models for Extended Objects},
	journal = {IEEE Trans. Knowl. Data Eng.},
	volume = {19},
	number = {8},
	year = {2007},
	pages = {1116{\textendash}1130},
	doi = {10.1109/TKDE.2007.1046},
	url = {https://doi.org/10.1109/TKDE.2007.1046},
	author = {Spiros Skiadopoulos and Nikos Sarkas and Timos K. Sellis and Manolis Koubarakis}
}
@article {593,
	title = {Fair Resource Allocation in a Simple Multi-Agent Setting: Search Algorithms and Experimental Evaluation},
	journal = {International Journal on Artificial Intelligence Tools (IJAIT)},
	volume = {14},
	year = {2005},
	month = {December},
	pages = {887{\textendash}899},
	abstract = {We study the problem of fair resource allocation in a simple cooperative multi-agent setting where we have k agents and a set of n objects to be allocated to those agents. Each object is associated with a weight represented by a positive integer or real number. We would like to allocate all objects to the agents so that each object is allocated to only one agent and the weight is distributed fairly. We adopt the fairness index popularized by the networking community as our measure of fairness, and study centralized algorithms for fair resource allocation. Based on the relationship between our problem and number partitioning, we devise a greedy algorithm for fair resource allocation that runs in polynomial time but is not guaranteed to find the optimal solution, and a complete anytime algorithm that finds the optimal solution but runs in exponential time. Then we study the phase transition behavior of the complete algorithm. Finally, we demonstrate that the greedy algorithm actually performs very well and returns almost perfectly fair allocations.},
	keywords = {Fairness; resource allocation; number partitioning; phase transitions},
	author = {Paraskevi Raftopoulou and Manolis Koubarakis and Kostas Stergiou and Peter Triantafillou}
}
@article {Souillard2005453,
	title = {A flexible framework for managing temporal clinical trial data},
	journal = {International Journal of Electronic Healthcare},
	volume = {1},
	number = {4},
	year = {2005},
	note = {cited By (since 1996) 2},
	pages = {453-463},
	abstract = {Clinical trials are processes that produce large volumes of complex data, with inherent temporal requirements, since the state of patients evolves during the trials, and the data acquisition phase itself needs to be monitored. Additionally, since the requirements for all clinical trials have a significant common portion, it is desirable to capture these common requirements in a generalised framework, which will be instantiated for each specific trial by supplementing the trial-specific requirements. In this paper, we present an integral approach to clinical trial management, using a temporal object-oriented methodology to capture and model the requirements, a temporal OODBMS for data storage and a generalised template application, through which trial-specific applications may be generated. Copyright Β{\textcopyright} 2005 Inderscience Enterprises Ltd.},
	keywords = {data base, information processing, medical information system, medical research, patient information, Quality control, review, telecommunication},
	doi = {10.1504/IJEH.2005.006691},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-21244469415\&partnerID=40\&md5=10bcf05c2826591c7ee952d0b3eecb1b},
	author = {Michael Souillard and Souveyet, C. and Costas Vassilakis and Anya Sotiropoulou}
}
@conference {lep03a,
	title = {Facilitating VR Museums Web Presence},
	booktitle = {Proceedings of HCI 2003},
	year = {2003},
	month = {6},
	pages = {1143{\textendash}1147},
	abstract = {The paper presents an environment that enables museum curators to catalogue and publish on the web exhibits in multiple languages and media including 3D, video, images. The system is extendable to accommodate new media types, languages, exhibits, information categories, etc. Visitors have the potential to formulate dynamic personalised exhibit collections using search mechanisms provided by the system.},
	author = {Giorgos Lepouras and Akrivi Katifori and Costas Vassilakis and Anna Charissi}
}
@article {Vassilakis2003315,
	title = {A framework for managing the lifecycle of transactional e-government services},
	journal = {Telematics and Informatics},
	volume = {20},
	number = {4},
	year = {2003},
	note = {cited By (since 1996) 13},
	pages = {315-329},
	abstract = {Filling and submission of electronic forms is a key issue for e-government, since most electronic services offered in this context include some variant of electronic forms. Insofar, IT experts are placed in the centre of electronic forms services lifecycles, undertaking the analysis, design, implementation and maintenance phases. This practice, however, implies various impediments, such as the need for multitudinous teams with diverse skills. In this paper, we present experiences from developing and maintaining a set of electronic services for the Greek Ministry of Finance, and propose an approach to handling electronic services{\textquoteright} lifecycle that balances responsibilities between domain experts and IT professionals. This approach enables a more holistic management of the electronic service lifecycle, by employing modelling and representation in high levels of abstraction and incorporating tools for automatically generating operative service instances from these high-level descriptions. Β{\textcopyright} 2003 Elsevier Science Ltd. All rights reserved.},
	keywords = {Communication, Electronic forms, Information science, Information technology},
	doi = {10.1016/S0736-5853(03)00011-X},
	url = {https://www.sciencedirect.com/science/article/abs/pii/S073658530300011X},
	author = {Costas Vassilakis and Laskaridis, G. and Giorgos Lepouras and S. Rouvas and P. Georgiadis}
}
@article {Kovacs2000417,
	title = {Function oriented history representation in databases},
	journal = {Computers and Artificial Intelligence},
	volume = {19},
	number = {5},
	year = {2000},
	note = {cited By (since 1996) 0},
	pages = {417-444},
	abstract = {In the past years the management of temporal data has attracted numerous researchers resulting to a large number of temporal data extensions to the relational and object oriented data models. In this paper, the proposed temporal data model focuses on the functional characteristics of the histories. The paper introduces a set oriented description of the calendars together with a function oriented history concept with a history-algebra. The completeness of the proposed model with respect to the reduced temporal algebra TA is also proven. The expressive power of the proposed model is demonstrated in the end of the paper by a hospital example.},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33751245138\&partnerID=40\&md5=575f314a008c5f0b9ae258689c3de7be},
	author = {Kovacs, L. and Costas Vassilakis}
}
