A novel Hybrid Recommender System for the tourism domainA novel Hybrid Recommender System for the tourism domain Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2025-04-242023enIn this paper, we develop a novel hybrid recommender system for the tourism domain, which combines (a) a Bayesian preferences elicitation component which operates by asking the user to rate generic images (corresponding to generic types of POIs) in order to build a user model and (b) a novel content-based (CB) recommendations component. The second component can in fact itself be considered a hybrid among two different CB algorithms, each exploiting one of two semantic similarity measures: a hierarchy-based and a non-hierarchy based one. The latter is the recently introduced Weighted Extended Jaccard Similarity (WEJS). We note that WEJS is employed for the first time within a recommender algorithm. We incorporate our algorithm within a real, already available at Google Play, tour-planning mobile application for short-term visitors of the popular touristic destination of Agios Nikolaos, Crete, Greece, and evaluate our approach via extensive simulations conducted on a real-world dataset constructed for the needs of the aforementioned mobile application. Our experiments verify that our algorithms result in effective personalized recommendations of touristic points of interest, while our final hybrid algorithm outperforms our exclusively content-based recommender algorithms in terms of recommendations accuracy. Specifically, when comparing the performance of several hybrid recommender system variants, we are able to come up with a “winner”: the most preferable variant of our hybrid recommender algorithm is one using a ⟨four elicitation slates, six shown images per slate⟩ pair as input to its Bayesian elicitation component. This variant combines increased precision performance with a lightweight preferences elicitation process.This research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH-CREATE-INNOVATE B cycle (project code: T2EDK-03135).http://creativecommons.org/licenses/by/4.0/Algorithms164Chalkiadakis_et_al_Algorithms_16(4)_2023.pdfChania [Greece]Library of TUC2025-04-24application/pdf4.5 MBfree Chalkiadakis Georgios Χαλκιαδακης Γεωργιος Ziogas Ioannis-Panagiotis Ζιωγας Ιωαννης-Παναγιωτης Koutsmanis Michail Κουτσμανης Μιχαηλ Streviniotis Errikos Στρεβινιωτης Ερρικος Panagiotakis Costas Papadakis Harris MDPI Hybrid recommender systems Bayesian recommenders Content-based recommendations Personalized recommendations Tourism recommenders Semantic similarity measures