Pavlos Kefalas

dblp:73/9344 · DBLP profile ↗
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19ranked-venue papers
5as first author
9since 2021 · last 2026
0000-0002-7197-1416ORCID · verified

Domains — the database's venue-derived domains; a paper can count in several

Artificial intelligence and machine learning · 12 · 1 first-author · 6 since 2021Databases, data management, data science and information retrieval · 6 · 2 first-author · 3 since 2021Applied, interdisciplinary, general and emerging computing · 3 · 2 first-authorTheory of computation · 1
YearPublicationVenuePosition
2026 Pythia-RAG: Retrieval-augmented generation over a unified multimodal knowledge graph for enhanced QA
Zafar Ali, Yi Huang 0017, Guilin Qi, Junlan Feng, Chao Deng 0002, Pavlos Kefalas
Knowl. Based Syst.8
2026 A citation recommendation model employing knowledge graph embedding
Zafar Ali, Guilin Qi, Sumaira Hussain, Irfan Ullah 0001, Shah Khalid, Adam A. Q. Mohammed, Inam Ullah 0001, Aalia Malik, Pavlos Kefalas
Soft Comput.9
2025 Improved paper recommendation model incorporating knowledge graph embedding with IRGAN model
abstract
The exponential growth of published papers in digital libraries has made finding relevant papers increasingly challenging for researchers. Numerous citation recommendation models have been developed to mitigate this issue and assist researchers in identifying pertinent works. Unfortunately, many of these models struggle to generate high-quality recommendations because they fail to capture diverse relationship patterns and effectively model the multifaceted relationships present in citation networks. Additionally, these models lack robustness in learning the representations of research papers. To address these limitations, we propose an innovative model that integrates graph embeddings to better understand hidden relationships in bibliographic networks and model multi-fold relations using the MRotatE framework. Our model first leverages graphical feature embeddings and content-based representations through MRotatE and SPECTER document embedding to construct initial representations of both query and candidate papers. These representations are then used in a generator and discriminator, which undergo adversarial training, ultimately resulting in improved recommendation outcomes. We evaluated our model against several baselines using three real-world datasets, and the results demonstrate that our approach outperforms existing models. The code for this project is publicly available online. 1
Nimbeshaho Thierry, Ingabire Batamira Christ Chatelain, Zafar Ali, Pavlos Kefalas
Trans. Recomm. Syst.4
2024 GLAMOR: Graph-based LAnguage MOdel embedding for citation Recommendation
abstract
Digital publishing’s exponential growth has created vast scholarly collections. Guiding researchers to relevant resources is crucial, and knowledge graphs (KGs) are key tools for unlocking hidden knowledge. However, current methods focus on external links between concepts, ignoring the rich information within individual papers. Challenges like insufficient multi-relational data, name ambiguity, and cold-start issues further limit existing KG-based methods, failing to capture the intricate attributes of diverse entities. To solve these issues, we propose GLAMOR, a robust KG framework encompassing entities e.g., authors, papers, fields of study, and concepts, along with their semantic interconnections. GLAMOR uses a novel random walk-based KG text generation method and then fine-tunes the language model using the generated text. Subsequently, the acquired context-preserving embeddings facilitate superior top@k predictions. Evaluation results on two public benchmark datasets demonstrate our GLAMOR’s superiority against state-of-the-art methods especially in solving the cold-start problem.
Zafar Ali, Guilin Qi, Irfan Ullah 0001, Adam A. Q. Mohammed, Pavlos Kefalas, Khan Muhammad 0001
RecSys5
2024 UTMGAT: a unified transformer with memory encoder and graph attention networks for multidomain dialogue state tracking
Bhuyan Kaibalya Prasad, Guilin Qi, Fanghua Ye 0001, Zafar Ali, Irfan Ullah 0001, Pavlos Kefalas
Appl. Intell.8
2023 PRM-KGED: paper recommender model using knowledge graph embedding and deep neural network
Nimbeshaho Thierry, Bing-Kun Bao, Zafar Ali, Zhiyi Tan 0002, Ingabire Batamira Christ Chatelain, Pavlos Kefalas
Appl. Intell.6
2022 Software defect prediction employing BiLSTM and BERT-based semantic feature
Md Nasir Uddin, Bixin Li, Zafar Ali, Pavlos Kefalas, Inayat Khan, Islam Zada
Soft Comput.4
2021 Global citation recommendation employing generative adversarial network
Zafar Ali, Guilin Qi, Khan Muhammad 0001, Pavlos Kefalas, Shah Khusro
Expert Syst. Appl.4
2021 RELINE: point-of-interest recommendations using multiple network embeddings
Giannis Christoforidis, Pavlos Kefalas, Apostolos N. Papadopoulos, Yannis Manolopoulos
Knowl. Inf. Syst.2
2020 Deep learning in citation recommendation models survey
Zafar Ali, Pavlos Kefalas, Khan Muhammad 0001, Bahadar Ali
Expert Syst. Appl.2
2019 Recommending Points of Interest in LBSNs Using Deep Learning Techniques
abstract
The representation of real-life problems by using k-partite graphs introduced a new era in Machine Learning. Moreover, the merge of virtual and physical layers through Location Based Social Networks (LBSN s) offers a different meaning into the constructed graphs. To this point, multiple models introduced in literature that aim to support users with personalized recommendations. These approaches represent the mathematical models that aim to understand users' behaviour by finding patterns on users' check-ins, reviews, ratings, friendships, etc. With this paper we describe and compare 20 of those state-of-the-art deep learning models to bring into the surface some of their strengths and shortcomings. First, we categorize them according to: data factors or features they use, data representation, methodologies used and recommendation types they support. Then, we highlight the existing limitations that tackles their performance. Finally, we introduce research trends and future directions.
Giannis Christoforidis, Pavlos Kefalas, Apostolos N. Papadopoulos, Yannis Manolopoulos
INISTA2
2018 Recommendation of Points-of-Interest Using Graph Embeddings
abstract
The rapid growth of Location-based Social Networks (LBSNs) has lead to the generation of massive datasets which are collected in an exponential rate. The collected information may be used to facilitate users' needs with recommendations related to their past preferences. Many recommendation models were introduced in the literature, which learn by the history of users and provide recommendations for Points-of-Interest. Unfortunately, most of them ignore the relation existing among the temporal properties, the spatial attributes and the periodicity of the check-ins. In this work, we present a novel methodology, named JLGE, that combines all aforementioned factors into one unified approach which facilitates POI recommendations. In particular, the model jointly learns the embeddings of six informational graphs i.e., two unipartite (user-user and POIPOI) and four bipartite (user-location, user-time, location-user, and location-time) into the same latent space and personalize the recommendations based on these embeddings. We have experimentally evaluated the accuracy of our model using two real-world datasets in terms of the top-n POIs recommendations. The performance evaluation results indicate a significant improvement in accuracy, in comparison to another state-of-theart graph-based approach.
Giannis Christoforidis, Pavlos Kefalas, Apostolos N. Papadopoulos, Yannis Manolopoulos
DSAA2
2018 Recommendations based on a heterogeneous spatio-temporal social network
Pavlos Kefalas, Panagiotis Symeonidis, Yannis Manolopoulos
World Wide Web1
2017 A time-aware spatio-textual recommender system
Pavlos Kefalas, Yannis Manolopoulos
Expert Syst. Appl.1
2017 Preference dynamics with multimodal user-item interactions in social media recommendation
Dimitrios Rafailidis, Pavlos Kefalas, Yannis Manolopoulos
Expert Syst. Appl.2
2016 A Graph-Based Taxonomy of Recommendation Algorithms and Systems in LBSNs
abstract
Recently, location-based social networks (LBSNs) gave the opportunity to users to share geo-tagged information along with photos, videos, and SMSs. Recommender systems can exploit this geographic information to provide much more accurate and reliable recommendations to users. In this paper, we present and compare 16 real life LBSNs, bringing into surface their advantages/ disadvantages, their special functionalities, and their impact in the mobile social Web. Moreover, we describe and compare extensively 43 state-of-the-art recommendation algorithms for LBSNs. We categorize these algorithms according to: personalization type, recommendation type, data factors/features, problem modeling methodology, and data representation. In addition to the above categorizations which cannot cover all algorithms in an integrated way, we also propose a hybrid k-partite graph taxonomy to categorize them based on the number of the involved k-partite graphs. Finally, we compare the recommendation algorithms with respect to their evaluation methodology (i.e., datasets and metrics) and we highlight new perspectives for future work in LBSNs.
Pavlos Kefalas, Panagiotis Symeonidis, Yannis Manolopoulos
IEEE Trans. Knowl. Data Eng.1
2015 Recommending Friends and Locations over a Heterogeneous Spatio-Temporal Graph
Pavlos Kefalas, Panagiotis Symeonidis
MEDI1
2013 New perspectives for recommendations in location-based social networks: time, privacy and explainability
abstract
Online social networks have attracted users' attention in the last decade. Recommendation services constitute a critical functionality of such social platforms: users receive recommendations about resources (documents, pieces of music) and potential friends (people with the same interests). Recently, technological progressions in smart phones enabled the exploitation of geographical data information in social networks. Users can now receive recommendations about new Points of Interest (POIs), and new activities in POIs. Eventually, Location-based Social Networks (LBSNs) may become the 'Next Big Thing' of the Internet industry. This paper surveys the related work and current state-of-the-art algorithms in LBSNs. We also provide three new perspectives that concern recommendations in LBSNs: time-awareness, user's privacy issues, and explainability of recommendations. We present the latest work in LBSNs by comparing real systems and by categorizing them in multiple ways (platforms, personalization, etc.).
Pavlos Kefalas, Panagiotis Symeonidis, Yannis Manolopoulos
MEDES1
2011 A tool for access to relational databases in natural language
Nikos Papadakis, Pavlos Kefalas, Manolis Stilianakakis
Expert Syst. Appl.2