VALID member chairs CONCEPTS 2026
Domingo López-Rodríguez (IP) co-chairs the programme committee of the 3rd Int J Conf on Conceptual Knowledge Structures (CONCEPTS), Montpellier (France), 2026. The conference proceedings can be accessed in this link.
In this edition, we participate as well with the organization of a tutorial about the package fcaR by our team member Manuel Ojeda-Hernández, Domingo López-Rodríguez and our colleague Ángel Mora; and the presentation of two key-works:
- L. Antoni, D. Kotlarová, O. Krídlo, D. López-Rodríguez and M. Ojeda-Aciego. Effective Greedy Boolean Matrix Factorization via the Rice-Siff Algorithm (presented by L'ubo)
- F. Valverde, C. Peláez-Moreno, I. P. Cabrera, P. Cordero and M. Ojeda-Aciego. Formal Context Transforms and Their Affordances for Exploratory Data Analysis (presented by Pablo Cordero).
As usual, the conference has been very inspiring and plenty of interaction with the attendants, see photos below
Participation CMMSE 2026
26th Int Conf on Computational and Mathematical Methods for Science and Engineering (CMMSE)
We participated with two presentations and the organisation of a special session.
The special session entitled Mathematical Methods in Computer Science, was co-organized by Jesús Medina (Univ. Cádiz) and Manuel Ojeda-Aciego.
Manuel Ojeda-Hernández presented the work Systems of implications obtained using the Carve decomposition of a formal context.
Manuel Ojeda-Aciego presented the work An FCA-based method for generating fuzzy RDF properties. 
PhD Prize award
Best PhD Prize awarded to team member
The University of Málaga has awarded our team member Manuel Ojeda-Hernández the Extraordinary PhD Prize in the category Mathematics.
Congratulations!!
Participation IPMU 2026
21st Int Conf on Information Processing and Management of Uncertainty in Knowledge-Based Systems (IPMU)
We participated with a key-work presentation and the organisation of a special session by Manuel Ojeda-Hernández.
The key-work was entitled How to build a direct-optimal system from a complete system of graded attribute implications.
In addition, we also participated organizing the special session on Knowledge representation and modelling, together with co-organizers Roberto Aragón and David Lobo.
Journal papers accepted COAM, IJAR
ABSTRACT This paper introduces a new Boolean Matrix Factorization (BMF) algorithm based on the Rice-Siff agglomerative clustering method. Our approach, Rice-Siff Factorization (RSF), integrates a greedy set-cover framework, where formal concepts serve as interpretable factors, with a dynamic candidate-generation process. By incorporating optimized variants such as RSF with Early Stopping (RSF-ES), we propose a pruning criterion based on order-theoretic properties to detect redundant candidates and significantly enhance factor extraction. Extensive synthetic benchmarks and experiments on real-world datasets demonstrate the effectiveness and robustness of the proposed framework, showing that RSF-ES provides significant scalability gains, yielding speedups on high-dimensional datasets with thousands of attributes while maintaining mathematical exactness. A comprehensive comparison with established factorization algorithms and an analysis of its theoretical properties show that RSF-ES represents a highly efficient and scalable solution for Boolean data analysis.
M. Ojeda-Hernández, D. López-Rodríguez. Direct-optimal systems of attribute implications in fuzzy formal concept analysis. Computational and Applied Mathematics 45:433, 2026
ABSTRACT Efficient closure computation is a key challenge in fuzzy Formal Concept Analysis. Direct implicational systems, which allow for one-step closure calculation, offer a powerful solution, but their formalization and practical computation in the fuzzy setting have remained largely open problems. This paper provides a comprehensive contribution to fill this gap. We first extend the concept of a direct system to fuzzy attribute implications and establish a complete theoretical characterization via a novel Fuzzy Exchange Condition. Building on this, we define the notion of a direct-optimal system and develop the DirectOptimal algorithm, a provably correct, interleaved strategy for its computation. A rigorous experimental evaluation demonstrates that our proposed algorithm is orders of magnitude more efficient than naive sequential approaches, and we diagnose the distinct computational bottlenecks that cause these simpler methods to fail. This work thus delivers a complete and empirically validated pipeline, from theory to practice, for the efficient computation of direct-optimal bases..
Participation IJCRS 2026
Intl Joint Conference of Rough Sets (IJCRS), May 25-28 2026, Cádiz, Spain
We participated with a communication, the organisation of a special session, and the presentation of a tutorial. The communication, with the title On a fuzzy inference system based on the notion of f -inclusion, was presented by Nicolás Madrid.
In the talk, the theoretical background of this type of FIS was recalled, together with a new result that asserts that the proposed system can be used for universal approximation of continuous functions.
In addition, Manuel Ojeda-Hernández participated in the organization of a Workshop on Conceptual structures and set approximations: A dialogue between Formal Concept Analysis and Rough Sets, together with co-organizers David Lobo and Dominika Kotlárova.
The tutorial fcaR: FCA for Knowledge Extraction in Real-World Environments was organised by Domingo López-Rodríguez and Ángel Mora, who was in charge of the presentation.
Last but not least, we had plenty of time to discuss scientific issues and potential collaboration with other colleagues. See below our table in the joint dinner together with Chris Cornelis (and Tanya), Davide Ciucci, Didier Dubois (and Genevieve), Salvatore Greco, Jesús Medina, Roberto Aragón, Maru Cornejo, Dominik Ślęzak and Yiyu Yao.
Journal papers accepted: INS
ABSTRACT This work extends our research on fuzzy relational Galois connections, previously established in the context of complete Heyting algebras, to the broader framework of arbitrary residuated lattices. In this context, we study the properties of fuzzy closure relations and fuzzy closure systems, and the relationship with fuzzy relational Galois connections. The main result of the paper is the generalization of the necessary and sufficient conditions for the existence of a right adjoint for a fuzzy relation linking a fuzzy transitive directed graph to an unstructured set.
Participation ESCIM 2026
Eur Symposium on Computer Intelligence and Mathematics (ESCIM), May 10-14 2026, Timișoara, Romania
We participated with a communication on the development of a package aimed at the application of Formal Concept Analysis, implemented in the R programming language. The title of the communication was Interactive Fuzzy FCA Recommender System: A Visual Approach using fcaR.
Traditional recommender systems often operate as black boxes, making them difficult to integrate into critical domains such as medical diagnosis,
where explainability is mandatory. This paper introduces an interactive recommendation framework based on the navigation of Fuzzy Formal Concept Lattices. Rather than relying on offline calculations or static rule sets, our approach implements a Guided Recommender Algorithm that allows experts to explore the knowledge structure iteratively. By applying a Local Zoom Strategy, the system extracts relevant sublattices in real-time, enabling users to refine searches through attributes with fuzzy degrees of certainty.
In addition, Manuel Ojeda-Hernández participated in the organization of a Special Session on Recent trends in knowledge representation and modelling, together with co-organizers David Lobo and Roberto G. Aragón.
Journal papers accepted FSS, INF
ABSTRACT Closure operators and systems play a significant role in a variety of areas of fuzzy logic. While the condition of monotony for ordinary closure operators has a straightforward form, two basic conditions of monotony naturally arise from the existing examples in a fuzzy setting. To unify these two conditions, two approaches can be found in the literature, one based on the notion of a filter of truth degrees and the other on the notion of a linguistic hedge. We present results connecting these approaches, explore their variants, and provide a notion of monotony that subsumes both the filter-based and hedge-based approaches. We study properties of this general concept of monotony and discuss open problems along with topics for future research.
M. Ojeda-Hernández, I.P. Cabrera, P. Cordero, E. Muñoz-Velasco. Characterising quasi-closed elements via closure systems on complete fuzzy lattices. Informatica, 2026 (to appear)
ABSTRACT The notion of quasi-closed element plays a central role in several branches of mathematics and computer sciences, for instance, in the Duquenne-Guigues basis of attribute implications. This paper deals with the extension of quasi-closed elements to the fuzzy setting by extending the well-known characterisation of quasi-closed elements in the crisp case, which is given in terms of closure systems. Specifically, we provide two distinct definitions, one considering crisp closure systems and another for fuzzy ones. Finally, we obtain a characterisation for each one of these notions..