Fuzzy Systems and Data Mining (FSDM) is a yearly well-established international conference dealing with four main groups of topics: a) fuzzy theory, algorithm and system, b) fuzzy application, c) interdisciplinary field of fuzzy logic and data mining and d) data mining. Following the great success of previous FSDM editions, which started in 2015, FSDM 2021 has become the seventh edition in the FSDM series, to be held in Seoul (South Korea) initially, and finally as an online conference, in a forum for experts, researchers, academics and industry people to introduce the last advances in the field of Fuzzy Sets and Data Mining. The most frequent topic this year is Fuzzy Systems.

This volume contains the papers accepted and presented at the 7th International Conference on Fuzzy Systems and Data Mining (FSDM 2021), held online on 26–29 October 2021, due to the pandemic. All papers were carefully reviewed by program committee members and took into account the breadth and depth of the research topics that fall into FSDM scopes. From 266 submissions, the 52 most promising and relevant contributions were included in this volume, which presents original ideas or results of general significance supported by clear reasoning and compelling evidence, and methods.

The conference program of FSDM 2021 includes keynote and invited presentations, oral and poster contributions. This event brought together more than 100 qualified and high-level researchers and experts from over 20 countries, including 6 keynote speakers, which created a good platform for researchers and engineers worldwide to enjoy academic communication.

I would like to thank all the keynote and invited speakers, authors and anonymous reviewers for putting their effort in preparing a contribution for the conference. We are also very grateful to the people, especially the program committee members and reviewers, who devoted time to assessing the papers. It is an honour to continue with the publication of these proceedings in the prestigious series Frontiers in Artificial Intelligence and Applications (FAIA) published by IOS Press. Our particular thanks also go to Joost Breuker, Nicola Guarino, Pascal Hitzler, Joost N. Kok, Jiming Liu, Ramon Lopez de Mantaras, Riichiro Mizoguchi, Mark Musen, Sankar K. Pal, Ning Zhong, who are the FAIA series editors, for supporting this conference.

Last but not least, I hope you enjoyed your online stay and first virtual contact with Seoul city, which may be followed with a face-to-face conference in Seoul in the future if the situation of the global pandemic of COVID-19 is brought under control.

Antonio J. Tallón-Ballesteros

University of Huelva, Spain