An International Journal in Information Science and Engineering
Official Publication of the International Fuzzy Systems Association (IFSA)

Since its launching in 1978, the journal Fuzzy Sets and Systems has been devoted to the international advancement of the theory and application of fuzzy sets and systems. The theory of fuzzy sets now encompasses a well organized corpus of basic notions including (and not restricted to) aggregation operations, a generalized theory of relations, specific measures of information content, a calculus of fuzzy numbers. Fuzzy sets are also the cornerstone of a non-additive uncertainty theory, namely possibility theory, and of a versatile tool for both linguistic and numerical modeling: fuzzy rule-based systems. Numerous works now combine fuzzy concepts with other scientific disciplines as well as modern technologies.

In mathematics fuzzy sets have triggered new research topics in connection with category theory, topology, algebra, analysis. Fuzzy sets are also part of a recent trend in the study of generalized measures and integrals, and are combined with statistical methods. Furthermore, fuzzy sets have strong logical underpinnings in the tradition of many-valued logics.

Fuzzy set-based techniques are also an important ingredient in the development of information technologies. In the field of information processing fuzzy sets are important in clustering, data analysis and data fusion, pattern recognition and computer vision. Fuzzy rule-based modeling has been combined with other techniques such as neural nets and evolutionary computing and applied to systems and control engineering, with applications to robotics, complex process control and supervision. In thefield of information systems, fuzzy sets play a role in the development of intelligent and flexible manBmachine interfaces and the storage of imprecise linguistic information. In Artificial Intelligence various forms of knowledge representation and automated reasoning frameworks benefit from fuzzy set-based techniques, for instance in interpolative reasoning, non-monotonic reasoning, diagnosis, logic programming, constraint-directed reasoning, etc. Fuzzy expert systems have been devised for fault diagnosis,and also in medical science. In decision and organization sciences, fuzzy sets has had a great impact in preference modeling and multicriteria evaluation, and has helped bringing optimization techniques closer to the users needs. Applications can be found in many areas such as management, production research, and finance. Moreover concepts and methods of fuzzy set theory have attracted scientists in many other disciplines pertaining to human-oriented studies such as cognitive psychology and some aspects of social sciences.

The scope of the journal Fuzzy Sets and Systems has expanded so as to account for all facets of the field while emphasizing its specificity as bridging the gap between the flexibility of human representations and the precision and clarity of mathematical or computerized representations, be they numerical or symbolic.

The journal welcomes original and significant contributions in the area of Fuzzy Sets whether on empirical or mathematical foundations, or their applications to any domain of information technology, and more generally to any field of investigation where fuzzy sets are relevant. Applied papers demonstrating the usefulness of fuzzy methodology in practical problems are particularly welcome. Fuzzy Sets and Systems publishes high-quality research articles, surveys as well as case studies. Separate sections are Recent Literature, and the Bulletin, which offers research reports, book reviews and conference announcements and various news items. Invited review articles on topics of general interest are included and special issues are published regularly.

Special Issue on Fuzzy Indices: New Developments in Theoretical, Computational, and Applied Topics
Submission Date: 2026-02-15

This special issue “Fuzzy indices: new developments in theoretical, computational and applied topics” will highlight the latest theoretical, computational and applied advancements in constructing indices based on fuzzy set theory. Over the past decade, a significant body of work has emerged on indices grounded in fuzzy set theory, demonstrating broad applicability across diverse fields, including economics and sociology. However, theoretical and computational progress has not consistently matched these applied developments. Many of the indices proposed to date exhibit excellent properties and practical value, yet their theoretical underpinnings remain relatively underexplored.

The aim of this special issue is to address this gap by providing a strong theoretical foundation to support the practical utility of fuzzy-set-based indices, which challenge traditional Aristotelian dichotomies. By establishing robust theoretical justifications, we hope to extend the legitimacy of these indices beyond mere philosophical discussions.

Guest editors:

Gianni Betti, University of Siena, Siena, Italy
Federico Crescenzi, University of Tuscia, Viterbo, Italy
Lorenzo Mori, University of Bologna, Bologna, Italy
Angeles Sánchez, University of Granada, Granada, Spain

Special issue information:

We encourage submissions that address one or more of the following areas:

    Development of novel membership functions tailored for socio-economic datasets with inherent fuzziness and imprecision.
    Exploration of statistical estimation methods for fuzzy data derived from probabilistic and nonprobabilistic sample surveys.
    Computational techniques for optimizing fuzzy set applications within social science contexts.
    Derivation of composite indicators based on fuzzy geometry.
    Machine learning and fuzzy metrics.
    Applications across emerging research areas such as inflation measurement, food and transport poverty, educational poverty, computational social science, energy efficiency, cyberbullying, gender equality metrics, etc.

Manuscript submission information:

Important Dates:

Submission Open Date: February 15, 2025
Final Submission Deadline: February 15, 2026
Editorial Acceptance Deadline: April 30, 2026

Authors should submit their manuscripts via the Fuzzy Sets and Systems journal submission portal (https://www.editorialmanager.com/fss/default.aspx), adhering to the standard formatting and review guidelines. All submissions will undergo a rigorous, single-anonymized peer review process managed by the Guest Editors. 

Please select the article type “VSI: Fuzzy Indices” when submitting your manuscript online, and refer to the Guide for Authors (https://www.sciencedirect.com/journal/fuzzy-sets-and-systems/publish/guide-for-authors) to prepare your manuscript.

For questions, please contact the guest editors at their institutional emails:

Gianni Betti: gianni.betti@unisi.it 
Federico Crescenzi: federico.crescenzi@unitus.it 
Lorenzo Mori: lorenzo.mori7@unibo.it 
Angeles Sánchez: sancheza@ugr.es 

Keywords:

Membership Functions, Fuzzy sets, Fuzzy indices, Socio-economic indicators