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..
Participation FSTA'26
Intl Conf on Fuzzy Sets Theory and Practice (FSTA'26). Liptovský Ján, Slovakia, January 25-30, 2026
Once again, we have attended the FSTA conference held in Liptovský Ján, in the Tatra Mountains of Slovakia. Our group presented one position paper “Generating Interpretable and User-elicited Fuzzy RDF Properties” and one key-work "Direct-optimal systems of attribute implications in fuzzy formal concept analysis".
As usual a very good conference with a nice atmosphere which invites to long conversations with colleagues. Below, in the left with Bernard De Baets (external collaborator) and Ondrej Krídlo (external collaborator); in the right, Vílem Novak and Irina Perlifieva (external collaborator) with Manuel Ojeda-Hernández and Zuzana Ontkovičová in the background.
Journal papers accepted FSS, COAM
ABSTRACT We analyze the use of the composition of mappings as a fuzzy conjunction between indexes of inclusion. Instead of the general approach of the φ-index of inclusion, we consider a fresh approach that computes the φ-index of inclusion when restricted to a join-subsemilattice of indexes of inclusion. Under this restriction, we identify a certain join-subsemilattice which has a biresiduated structure when composition is interpreted as conjunction. The main consequence of this biresiduated structure is a representation theorem of biresiduated lattices on the unit interval in terms of the composition and subsets of indexes of inclusion.
H. Bello, P. Jiménez, C. Bejines. Examining fuzzy number approximation through a topological algebraic approach. Computational and Applied Mathematics 45, 81 (2026).
ABSTRACT In this paper, we delve into the study of fuzzy number approximation by LR fuzzy numbers, shedding light on their algebraic properties. We present a solid approach to approximate fuzzy numbers keeping the same expected interval and core proving that such approximation is additive and continuous under a wide family of distances. As a key part of this construction, we study the set of fuzzy numbers as a topological monoid and develop a process to embed any cancellative abelian topological monoid with open shifts in a topological abelian group. This allows us to demonstrate a highly useful result in the context of this paper: the continuity of homomorphisms between cancellative topological abelian monoids with open shifts is equivalent to its continuity at zero.
D. López-Rodríguez, M. Ojeda-Hernández, A. Mora, C. Bejines. Close-by-One-like algorithms in the fuzzy setting: Theory and experimentation. Fuzzy Sets and Systems 520, Article 109574, 2025.
ABSTRACT In Fuzzy Formal Concept Analysis (FFCA), concept lattices are computed by scaling the problem and applying ordinary FCA algorithms. In this paper, the CbO family of algorithms is extended to work natively in the fuzzy setting, they are proved to be correct and output the whole set of formal concepts, which makes them mathematically equivalent to the scaling approach.
However, experimental results demonstrate the performance improvement of these methods compared to scaling. The paper also discusses a new fuzzy strategy based on blacklisting redundant truth values to enhance the performance of algorithms by taking advantage of the structure of the residuated lattice.
Conference contributions accepted FSTA
EXTENDED ABSTRACT
M. Ojeda-Hernández. Direct-optimal systems of attribute implications in fuzzy Formal Concept Analysis. Fuzzy Set Theory and Applications (FSTA), Liptovský Ján, Slovak Republic, 2026.
EXTENDED ABSTRACT
Participation CONCEPTS'25
Intl Joint Conf on Conceptual Knowledge Structures (Concepts'25). Cluj-Napoca, Romania, September 8-12, 2025
Back from the conference Concepts’25 held in the Babeș-Bolyai University. Our group organized the workshop “Late Breaking Advances on Conceptual Structures” and presented the keywork “Systems of implications obtained using the Carve decomposition of a formal context”.
A very good conference with a lot of interesting presentations and discussions, and even an open problem posed by Prof Bernhard Ganter (let's see what happens with it).
