Symeon Papadopoulos

Dr. Symeon Papadopoulos

Centre for Research and Technology Hellas, Thessaloníki, Kentrikí Makedonía, Greece
orcid

Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
3 February 2020 in WIREs Data Mining and Knowledge Discovery
Verified
Journal Article
Open access
PDF file
ENEirini Ntoutsi
Eirini Ntoutsi
PFPavlos Fafalios
Pavlos Fafalios
UGUjwal Gadiraju
Ujwal Gadiraju
VIVasileios Iosifidis
Vasileios Iosifidis
WNWolfgang Nejdl
Wolfgang Nejdl
SSSteffen Staab
Steffen Staab
Artificial Intelligence (AI)‐based systems are widely employed nowadays to make decisions that have far‐reaching impact on individuals and society. Their decisions might affect everyone, everywhere, and anytime, entailing concerns about potential human rights issues. Therefore, it is necessary to move beyond traditional AI algorithms optimized for predictive performance and embed ethical and legal principles in their design, training, and deployment to ensure social good while still benefiting from the huge potential of the AI technology. The goal of this survey is to provide a broad multidisciplinary overview of the area of bias in AI systems, focusing on technical challenges and solutions as well as to suggest new research directions towards approaches well‐grounded in a legal frame. In this survey, we focus on data‐driven AI, as a large part of AI is powered nowadays by (big) data and powerful machine learning algorithms. If otherwise not specified, we use the general term bias to describe problems related to the gathering or processing of data that might result in prejudiced decisions on the bases of demographic features such as race, sex, and so forth.This article is categorized under: Commercial, Legal, and Ethical Issues > Fairness in Data Mining Commercial, Legal, and Ethical Issues > Ethical Considerations Commercial, Legal, and Ethical Issues > Legal Issues

14 June 2011 in Data Mining and Knowledge Discovery
Verified
Journal Article
Closed access
PDF file
Symeon PapadopoulosSymeon Papadopoulos
Symeon Papadopoulos
Ioannis KompatsiarisIoannis Kompatsiaris
Ioannis Kompatsiaris
AVAthena Vakali
Athena Vakali
PSPloutarchos Spyridonos
Ploutarchos Spyridonos

6 June 2013 in IEEE Transactions on Multimedia
Verified
Journal Article
Closed access
LALuca Maria Aiello
Luca Maria Aiello
GPGeorgios Petkos
Georgios Petkos
CMCarlos Martin
Carlos Martin
DCDavid Corney
David Corney
Symeon PapadopoulosSymeon Papadopoulos
Symeon Papadopoulos
AJAlejandro Jaimes
Alejandro Jaimes
Online social and news media generate rich and timely information about real-world events of all kinds. However, the huge amount of data available, along with the breadth of the user base, requires a substantial effort of information filtering to successfully drill down to relevant topics and events. Trending topic detection is therefore a fundamental building block to monitor and summarize information originating from social sources. There are a wide variety of methods and variables and they greatly affect the quality of results. We compare six topic detection methods on three Twitter datasets related to major events, which differ in their time scale and topic churn rate. We observe how the nature of the event considered, the volume of activity over time, the sampling procedure and the pre-processing of the data all greatly affect the quality of detected topics, which also depends on the type of detection method used. We find that standard natural language processing techniques can perform well for social streams on very focused topics, but novel techniques designed to mine the temporal distribution of concepts are needed to handle more heterogeneous streams containing multiple stories evolving in parallel. One of the novel topic detection methods we propose, based on -grams cooccurrence and topic ranking, consistently achieves the best performance across all these conditions, thus being more reliable than other state-of-the-art techniques.

19 October 2021 in Computing
Verified
Journal Article
Open access
PDF file
AFAsbjørn Følstad
Asbjørn Følstad
TATheo Araujo
Theo Araujo
ELEffie Lai-Chong Law
Effie Lai-Chong Law
PBPetter Bae Brandtzaeg
Petter Bae Brandtzaeg
Symeon PapadopoulosSymeon Papadopoulos
Symeon Papadopoulos
ELEwa Luger
Ewa Luger
Chatbots are increasingly becoming important gateways to digital services and information—taken up within domains such as customer service, health, education, and work support. However, there is only limited knowledge concerning the impact of chatbots at the individual, group, and societal level. Furthermore, a number of challenges remain to be resolved before the potential of chatbots can be fully realized. In response, chatbots have emerged as a substantial research area in recent years. To help advance knowledge in this emerging research area, we propose a research agenda in the form of future directions and challenges to be addressed by chatbot research. This proposal consolidates years of discussions at the CONVERSATIONS workshop series on chatbot research. Following a deliberative research analysis process among the workshop participants, we explore future directions within six topics of interest: (a) users and implications, (b) user experience and design, (c) frameworks and platforms, (d) chatbots for collaboration, (e) democratizing chatbots, and (f) ethics and privacy. For each of these topics, we provide a brief overview of the state of the art, discuss key research challenges, and suggest promising directions for future research. The six topics are detailed with a 5-year perspective in mind and are to be considered items of an interdisciplinary research agenda produced collaboratively by avid researchers in the field.

4 December 2017 in International Journal of Multimedia Information Retrieval
Verified
Journal Article
Open access
PDF file
CBChristina Boididou
Christina Boididou
Symeon PapadopoulosSymeon Papadopoulos
Symeon Papadopoulos
MZMarkos Zampoglou
Markos Zampoglou
LALazaros Apostolidis
Lazaros Apostolidis
OPOlga Papadopoulou
Olga Papadopoulou
YKYiannis Kompatsiaris
Yiannis Kompatsiaris
The problems of online misinformation and fake news have gained increasing prominence in an age where user-generated content and social media platforms are key forces in the shaping and diffusion of news stories. Unreliable information and misleading content are often posted and widely disseminated through popular social media platforms such as Twitter and Facebook. As a result, journalists and editors are in need of new tools that can help them speed up the verification process for content that is sourced from social media. Motivated by this need, in this paper, we present a system that supports the automatic classification of multimedia Twitter posts into credible or misleading. The system leverages credibility-oriented features extracted from the tweet and the user who published it, and trains a two-step classification model based on a novel semisupervised learning scheme. The latter uses the agreement between two independent pretrained models on new posts as guiding signals for retraining the classification model. We analyze a large labeled dataset of tweets that shared debunked fake and confirmed real images and videos, and show that integrating the newly proposed features, and making use of bagging in the initial classifiers and of the semisupervised learning scheme, significantly improves classification accuracy. Moreover, we present a Web-based application for visualizing and communicating the classification results to end users.

1 September 2016 in Multimedia Tools and Applications
Verified
Journal Article
Closed access
PDF file
MZMarkos Zampoglou
Markos Zampoglou
Symeon PapadopoulosSymeon Papadopoulos
Symeon Papadopoulos
Ioannis KompatsiarisIoannis Kompatsiaris
Ioannis Kompatsiaris