Publications | Pablo Castells

2020

J. Sanz-Cruzado, P. Castells, C. Macdonald, I. Ounis. Effective Contact Recommendation in Social Networks by Adaptation of Information Retrieval Models. Information Processing & Management 57(5), September 2020.

(BibTeX | Tags: recommender systems, information retrieval models, social networks, contact recommendation, learning to rank)

E. K. Mena, R. Cañamares, P. Castells, Y. Ren, M. Sanderson. Agreement and Disagreement between True and False-Positive Metrics in Recommender Systems Evaluation. 43rd International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2020). Xian, China, July 2020.

(BibTeX | Tags: recommender systems, metrics, evaluation, popularity, bias, non-random missing data, false positive)

J. Sanz-Cruzado, C. Macdonald, I. Ounis, P. Castells. Axiomatic Analysis of Contact Recommendation Methods in Social Networks: an IR perspective. 42th European Conference on Information Retrieval (ECIR 2020), Springer Verlag Lecture Notes in Computer Science, Vol. 12035. Lisbon, Portugal, April 2020, ISBN: 978-3-030-45439-5, pp. 175-90.

(BibTeX | Tags: recommender systems, social networks, information retrieval, contact recommendation, axiomatic information retrieval)

R. Cañamares, P. Castells, A. Moffat. Offine Evaluation Options for Recommender Systems. Information Retrieval, in press, 2020.

(BibTeX | Tags: recommender systems, evaluation)

D. Valcarce, A. Bellogín, J. Parapar, P. Castells. Assessing ranking metrics in top-N recommendation. Information Retrieval, in press, 2020.

(BibTeX | Tags: recommender systems, metrics, evaluation)

2019

J. Sanz-Cruzado, P. Castells, E. López. A Simple Multi-Armed Nearest-Neighbor Bandit for Interactive Recommendation. 13th ACM Conference on Recommender Systems (RecSys 2019). Copenhagen, Denmark, September 2019, pp. 358-362.
Poster

(BibTeX | Tags: recommender systems, knn, multi-armed bandits, thompson sampling, interactive recommendation)

R. Cañamares, M. Redondo, P. Castells. Multi-Armed Recommender System Bandit Ensembles. 13th ACM Conference on Recommender Systems (RecSys 2019). Copenhagen, Denmark, September 2019, pp. 432-436.
Poster

(BibTeX | Tags: recommender systems, multi-armed bandits, ensembles, hybrid recommender systems, feedback loop, interactive re)

J. Sanz-Cruzado, P. Castells. Information Retrieval Models for Contact Recommendation in Social Networks. 41st European Conference on Information Retrieval (ECIR 2019), Springer Verlag Lecture Notes in Computer Science, Vol. 11437. Cologne, Germany, April 2019, ISBN: 978-3-030-15711-1, pp. 148-163.
Slides

(BibTeX | Tags: recommender systems, information retrieval models, social networks, information retrieval, contact recommendation)

J. Sanz-Cruzado, P. Castells. Beyond Accuracy in Link Prediction. 3rd Workshop on Social Media for Personalization And Search (SoMePeAS 2019) at the 41st European Conference on Information Retrieval (ECIR 2019). Cologne, Germany, April 2019.

(BibTeX | Tags: novelty, diversity, recommender systems, evaluation, social networks, link prediction, contact recommendation)

2018

J. Sanz-Cruzado, P. Castells. Contact Recommendations in Social Networks. In S. Berkovsky, I. Cantador, D. Tikk (Eds.): Collaborative Recommendations: Algorithms, Practical Challenges and Applications. World Scientific Publishing, November 2018, ISBN: 978-981-3275-35-5, pp. 519-569.

(BibTeX | Tags: recommender systems, evaluation, social networks, link prediction, contact recommendation)

P. Castells, R. Cañamares. Characterization of Fair Experiments for Recommender System Evaluation – A Formal Analysis. Workshop on Offline Evaluation for Recommender Systems (REVEAL 2018) at the 12th ACM Conference on Recommender Systems (RecSys 2018). Vancouver, Canada, October 2018.
Poster

(BibTeX | Tags: recommender systems, evaluation, popularity, information retrieval theory, bias, non-random missing data)

J. Sanz-Cruzado, P. Castells. Enhancing Structural Diversity in Social Networks by Recommending Weak Ties. 12th ACM Conference on Recommender Systems (RecSys 2018). Vancouver, Canada, October 2018, pp. 233-241.
Slides | Poster

(BibTeX | Tags: novelty, diversity, recommender systems, evaluation, social networks, contact recommendation)

D. Valcarce, A. Bellogín, J. Parapar, P. Castells. On the Robustness and Discriminative Power of IR Metrics for Top-N Recommendation. 12th ACM Conference on Recommender Systems (RecSys 2018). Vancouver, Canada, October 2018, pp. 260-268.

(BibTeX | Tags: recommender systems, metrics, evaluation)

R. Cañamares, P. Castells. Should I Follow the Crowd? A Probabilistic Analysis of the Effectiveness of Popularity in Recommender Systems. 41st Annual International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2018). Ann Arbor, Michigan, USA, July 2018, pp. 415-424 — best paper award.
Slides

(BibTeX | Tags: recommender systems, evaluation, information retrieval, popularity, information retrieval theory, bias, non-random missing data)

R. Cañamares, P. Castells. From the PRP to the Low Prior Discovery Recall Principle for Recommender Systems. 41st Annual International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2018). Ann Arbor, Michigan, USA. July 2018, pp. 1081-1084.
Poster

(BibTeX | Tags: novelty, recommender systems, metrics, evaluation, information retrieval, popularity, information retrieval theory)

J. Sanz-Cruzado, S. M. Pepa, P. Castells. Structural Novelty and Diversity in Link Prediction. 9th International Workshop on Modeling Social Media (MSM 2018) at The Web Conference (TheWebConf 2018). Lyon, France, April 2018.

(BibTeX | Tags: novelty, diversity, recommender systems, evaluation, social networks, link prediction)

2017

R. Cañamares, P. Castells. On the Optimal Non-Personalized Recommendation: From the PRP to the Discovery False Negative Principle. ACM SIGIR 2017 Workshop on Axiomatic Thinking for Information Retrieval and Related Tasks (ATIR 2017). Tokyo, Japan, August 2017.

(BibTeX | Tags: recommender systems, evaluation, popularity, information retrieval theory, probability ranking principle)

A. Bellogín, P. Castells, I. Cantador. Statistical Biases in Information Retrieval Metrics for Recommender Systems. Information Retrieval 20(6), July 2017, pp. 606-634.

(BibTeX | Tags: recommender systems, evaluation, popularity)

2015

P. Castells, N. J. Hurley, S. Vargas. Novelty and Diversity in Recommender Systems. In Francesco Ricci, Lior Rokach, Bracha Shapira (Eds.): Recommender Systems Handbook, 2nd edition. Springer, 2015, ISBN: 978-1-4899-7637-6, pp. 881-918.

(BibTeX | Tags: novelty, diversity, recommender systems, evaluation, information retrieval)

2014

S. Vargas, L. Baltrunas, A. Karatzoglou, P. Castells. Coverage, Redundancy and Size-Awareness in Genre Diversity for Recommender Systems. 8th ACM Conference on Recommender Systems (RecSys 2014). Foster City, CA, USA, October 2014, pp. 209-216.
Slides | Poster

(BibTeX | Tags: novelty, diversity, recommender systems, evaluation)

S. Vargas, P. Castells. Improving Sales Diversity by Recommending Users to Items. 8th ACM Conference on Recommender Systems (RecSys 2014). Foster City, CA, USA, October 2014, pp. 145-152.
Slides | Poster

(BibTeX | Tags: novelty, diversity, recommender systems, collaborative filtering)

R. Cañamares, P. Castells. Exploring social network effects on popularity biases in recommender systems. 6th Workshop on Recommender Systems and the Social Web (RSWeb 2014) at the 8th ACM Conference on Recommender Systems (RecSys 2014). Foster City, CA, USA, October 2014.

(BibTeX | Tags: recommender systems, evaluation, social networks)

A. Bellogín, P. Castells, I. Cantador. Neighbor Selection and Weighting in User-Based Collaborative Filtering: A Performance Prediction Approach. ACM Transactions on the Web 8(2), March 2014.

(BibTeX | Tags: recommender systems, collaborative filtering, performance prediction, information retrieval)

2013

A. Bellogín, J. Wang, P. Castells. Bridging Memory-Based Collaborative Filtering and Text Retrieval. Information Retrieval 16(6), December 2013, pp. 697-724.

(BibTeX | Tags: recommender systems, collaborative filtering, information retrieval models, information retrieval)

A. Bellogín, J. Parapar, P. Castells. Probabilistic Collaborative Filtering with Negative Cross Entropy. 7th ACM Conference on Recommender Systems (RecSys 2013). Hong Kong, China, October 2013, pp. 387-390.

(BibTeX | Tags: recommender systems, collaborative filtering, information retrieval models, information retrieval)

J. Parapar, A. Bellogín, P. Castells, A. Barreiro. Relevance-Based Language Modelling for Recommender Systems. Information Processing & Management 49(4), July 2013.

(BibTeX | Tags: recommender systems, collaborative filtering, information retrieval models, information retrieval)

S. Vargas, P. Castells. Exploiting the Diversity of User Preferences for Recommendation. 10th International Conference in the RIAO series (OAIR 2013). Lisbon, Portugal, May 2013.
Slides

(BibTeX | Tags: diversity, recommender systems, web services, user profile)

A. Bellogín, I. Cantador, P. Castells, F. Díez. Exploiting Social Networks in Recommendation: a Multi-Domain Comparison. 13th Dutch-Belgian Information Retrieval Workshop (DIR 2013). Delft, Netherlands, April 2013.

(BibTeX | Tags: recommender systems, evaluation, collaborative filtering, social networks, context)

A. Bellogín, I. Cantador, F. Díez, P. Castells, E. Chavarriaga. An Empirical Comparison of Social, Collaborative Filtering, and Hybrid Recommenders. ACM Transactions on Intelligent Systems and Technology 4(1), special issue on Context-Aware Movie Recommendations, February 2013.

(BibTeX | Tags: recommender systems, social networks, hybrid recommendation)

A. Bellogín, I. Cantador, P. Castells. A Comparative Study of Heterogeneous Item Recommendations in Social Systems. Information Sciences 221(1), February 2013, pp. 142-169.

(BibTeX | Tags: novelty, diversity, recommender systems, evaluation, collaborative filtering, social networks)

2012

I. Cantador, P. Castells. Group Recommender Systems: New Perspectives in the Social Web. In J. J. Pazos Arias, A. Fernández Vilas, R. P. Díaz Redondo (Eds.): Recommender Systems for the Social Web. Springer Verlag, Intelligent Systems Reference Library, Vol. 32, 2012, ISBN: 978-3-642-25693-6, pp. 139-157.

(BibTeX | Tags: recommender systems, social web, group recommendation)

2011

A. Bellogín, P. Castells, I. Cantador. Precision-Oriented Evaluation of Recommender Systems: An Algorithmic Comparison. 5th ACM Conference on Recommender Systems (RecSys 2011). Chicago, Illinois, October 2011, pp. 333-336.

(BibTeX | Tags: recommender systems, metrics, evaluation, experimental methodology)

S. Vargas, P. Castells. Rank and Relevance in Novelty and Diversity Metrics for Recommender Systems. 5th ACM Conference on Recommender Systems (RecSys 2011). Chicago, Illinois, October 2011, pp. 109-116.
Slides

(BibTeX | Tags: novelty, diversity, recommender systems, metrics, evaluation)

A. Bellogín, J. Wang, P. Castells. Structured Collaborative Filtering. 20th ACM International Conference on Information and Knowledge Management (CIKM 2011). Glasgow, UK, October 2011, pp. 2257-2260.

(BibTeX | Tags: recommender systems, collaborative filtering, information retrieval models, information retrieval)

A. Bellogín, P. Castells, I. Cantador. Predicting the Performance of Recommender Systems: An Information Theoretic Approach. 3rd International Conference on the Theory of Information Retrieval (ICTIR 2011) - Springer Verlag Lecture Notes in Computer Science, Vol. 6931. Bertinoro, Italy, September 2011, ISBN: 978-3-642-23317-3, pp. 27-39.

(BibTeX | Tags: recommender systems, performance prediction, information retrieval)

S. Vargas, P. Castells, D. Vallet. Intent-Oriented Diversity in Recommender Systems. 34th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2011). Beijing, China, July 2011, pp. 1211-1212.
Poster

(BibTeX | Tags: diversity, recommender systems, metrics, evaluation, information retrieval)

A. Bellogín, P. Castells, I. Cantador. Self-adjusting Hybrid Recommenders Based on Social Network Analysis. 34th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2011). Beijing, China, July 2011, pp. 1147-1148.

(BibTeX | Tags: recommender systems, performance prediction, social networks, hybrid recommendation)

I. Cantador, P. Castells. Extracting Multilayered Communities of Interest from Semantic User Profiles: Application to Group Modeling and Hybrid Recommendations. Computers in Human Behavior 27(4), special issue on Social and Humanistic Computing for the Knowledge Society, July 2011, pp. 1321-1336.

(BibTeX | Tags: recommender systems, hybrid recommendation, semantics, community detection, group recommendation)

P. Castells, S. Vargas, J. Wang. Novelty and Diversity Metrics for Recommender Systems: Choice, Discovery and Relevance. International Workshop on Diversity in Document Retrieval (DDR 2011) at the 33rd European Conference on Information Retrieval (ECIR 2011). Dublin, Ireland, April 2011.

(BibTeX | Tags: novelty, diversity, recommender systems, metrics, evaluation, information retrieval)

A. Bellogín, I. Cantador, P. Castells, Á. Ortigosa. Discerning Relevant Model Features in a Content-based Collaborative Recommender System. In J. Fürnkranz, E. Hüllermeier (Eds.): Preference Learning. Springer Verlag, 2011, ISBN: 978-3-642-14124-9, pp. 429-456.

(BibTeX | Tags: recommender systems, collaborative filtering, content-based recommendation)

I. Cantador, P. Castells, A. Bellogín. An Enhanced Semantic Layer for Hybrid Recommender Systems: Application to News Recommendation. International Journal on Semantic Web and Information Systems 7(1), 2011, pp. 44-78.

(BibTeX | Tags: recommender systems, hybrid recommendation, semantics, news retrieval)

2010

A. Bellogín, P. Castells. A Performance Prediction Approach to Enhance Collaborative Filtering Performance. 32nd European Conference on Information Retrieval (ECIR 2010), Springer Verlag Lecture Notes in Computer Science, Vol. 5993. Milton Keynes, UK, May 2010, ISBN: 978-3642122743, pp. 382-393.

(BibTeX | Tags: recommender systems, collaborative filtering, performance prediction)

2009

A. Bellogín, P. Castells. Predicting Neighbor Goodness in Collaborative Filtering. 8th International Conference on Flexible Query Answering Systems (FQAS 2009), Springer Verlag Lecture Notes in Computer Science, Vol. 5822. Roskilde, Denmark, October 2009, ISBN: 978-3-642-04956-9, pp. 605-616.

(BibTeX | Tags: recommender systems, collaborative filtering, performance prediction)

I. Cantador, P. Castells. Semantic Contextualisation in a News Recommender Systems. Workshop on Context-Aware Recommender Systems (CARS 2009) at the 3rd ACM Conference on Recommender Systems (RecSys 2009). New York, NY, USA, October 2009.

(BibTeX | Tags: recommender systems, context, news retrieval)

2008

I. Cantador, A. Bellogín, P. Castells. Ontology-based Personalised and Context-aware Recommendations of News Items. IEEE/WIC/ACM International Conference on Web Intelligence (WI 2008). Sydney, Australia, December 2008.

(BibTeX | Tags: recommender systems, context, semantics, news retrieval)

A. Bellogín, I. Cantador, P. Castells, A. Ortigosa. Discovering Relevant Preferences in a Personalised Recommender System using Machine Learning Techniques. Preference Learning Workshop (PL 2008), at the 8th European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML PKDD 2008). Antwerp, Belgium, September 2008, pp. 82-96.

(BibTeX | Tags: recommender systems, machine learning)

I. Cantador, A. Bellogín, P. Castells. News@hand: A Semantic Web Approach to Recommending News. 5th International Conference on Adaptative Hypermedia (AH 2008), Springer Verlag Lecture Notes in Computer Science, Vol. 5149. Hannover, Germany, July 2008, ISBN: 978-3-540-70984-8, pp. 279-283.

(BibTeX | Tags: recommender systems, semantics, news retrieval)

I. Cantador, M. Szomszor, H. Alani, M. Fernández, P. Castells. Enriching Ontological User Profiles with Tagging History for Multi-Domain Recommendations. 1st International Workshop on Collective Semantics: Collective Intelligence and the Semantic Web (CISWeb 2008), at the 5th European Semantic Web Conference (ESWC 2008). Tenerife, Spain, June 2008, pp. 5-19.

(BibTeX | Tags: recommender systems, personalization, semantics)

I. Cantador, A. Bellogín, P. Castells. A Multilayer Ontology-based Hybrid Recommendation Model. AI Communications 21(2-3), special issue on Recommender Systems, April 2008, pp. 203-210.

(BibTeX | Tags: recommender systems, hybrid recommendation, semantics)

2007

I. Cantador, P. Castells, A. Bellogín. Modelling Ontology-based Multilayered Communities of Interest for Hybrid Recommendations. 1st Workshop on Adaptation and Personalization in Social Systems: Groups, Teams, Communities (SociUM 2007) at the 11th International Conference on User Modeling (UM 2007). Corfu, Greece, June 2007.

(BibTeX | Tags: recommender systems, hybrid recommendation, semantics)

I. Cantador, M. Fernández, P. Castells. Improving Ontology Recommendation and Reuse in WebCORE by Collaborative Assessments. Workshop on Social and Collaborative Construction of Structured Knowledge at the 16th International World Wide Web Conference (WWW 2007). Banff, Canada, May 2007.

(BibTeX | Tags: recommender systems, collaborative filtering, semantics, collaborative systems)

2006

I. Cantador, P. Castells. Multilayered Semantic Social Network Modeling by Ontology-Based User Profiles Clustering: Application to Collaborative Filtering. 15th International Conference on Knowledge Engineering and Knowledge Management (EKAW 2006). Springer Verlag Lecture Notes in Computer Science, Vol. 4248. Podebrady, Czech Republic, October 2006, ISSN: 3-540-46363-1, pp. 334-349.

(BibTeX | Tags: recommender systems, collaborative filtering, social networks, semantics)

I. Cantador, M. Fernández, P. Castells. A Collaborative Recommendation Framework for Ontology Evaluation and Reuse. International Workshop on Recommender Systems at the 17th European Conference on Artificial Intelligence (ECAI 2006). Riva del Garda, Italy, August 2006.

(BibTeX | Tags: recommender systems, collaborative filtering, semantics, collaborative systems)

I. Cantador, P. Castells, D. Vallet. Enriching Group Profiles with Ontologies for Knowledge-Driven Collaborative Content Retrieval. 1st Int. Workshop on Semantic Technologies in Collaborative Applications (STICA 2006), at the 15th IEEE Workshops on Enabling Technologies: Infrastructures for Collaborative Enterprises (WETICE 2006). Manchester, UK, June 2006.

(BibTeX | Tags: recommender systems, collaborative filtering, information retrieval, semantics, group recommendation)

I. Cantador, P. Castells. Multilayered Ontology-Based User Profiles and Semantic Social Networks for Recommender Systems. 2nd Int. Workshop on Web Personalisation, Recommender Systems and Intelligent User Interfaces (WPRSIUI 2006) at the 4th Int. Conf. on Adaptive Hypermedia and Adaptive Web-Based Systems (AH 2006). Dublin, Ireland, June 2006.

(BibTeX | Tags: recommender systems, social networks, semantics)