Bidirectional transformation, a mechanism to synchronise multiple data sources in different formats, is a recurring concept in software development and has various applications, including the classic view-update problem in database systems, along with synchronisation and communication in database systems, GUI/web application development, implementation of serialisers, compiler frontend, and model-driven software development. Accordingly, bidirectional transformations have been studied in multiple research disciplines, including databases, programming languages, software engineering, graph transformations, and applied mathematics, from various perspectives, such as:

• Construction of bidirectional transformations: including programming languages and systems (such as lenses and triple graph grammars), type systems, program synthesis (programming by example), program transformations to construct bidirectional programs from unidirectional ones, programming frameworks, and programming methodologies.

•  Applications of bidirectional transformations: including synchronisation of software artefacts (such as object-oriented models) created in the software development process, tooling to support such applications, the classic view-update problem on relational databases or more modern architectures, incremental view maintenance, exploration of design space and data exchanges between databases.

• Foundations of bidirectional transformations: including mathematical models of bidirectional transformations which arose in various fields including those above, abstractions, properties and theorems, and mechanised formalisation of such approaches in theorem provers such as Coq/Lean/Agda.

These topics have their own right and have mainly been studied intensively in each community, but these perspectives share interests, goals, challenges, and techniques and have strong synergy; well-designed construction methods encourage applications and provide hints for abstractions, applications suggest directions to which construction methods and foundations to evolve and serve as benchmarks, and mathematical foundations suggest new designs of construction methods and application design which are effective for various forms of consistency of systems.

The focus of this Shonan meeting is to provide researchers from different disciplines an opportunity to meet up, exchange ideas, and network groups, renewing and boosting the results from the previous meeting held with the same spirit (2011 Dagstuhl, 2013 Banff, 2016 Shonan, 2018 Dagstuhl), and from the series of the BX workshops (2012 Estonia, 2013 Italy, 2014 Greece, 2015 Italy, 2016 Netherlands, 2017 Sweden, 2018 France, 2019 USA, 2021 Online, 2022 France). It has been 6 years since the last BX meeting at Dagstuhl, and there have been a lot of research results in each field, justifying the importance of this Shonan meeting.

The organisers are part of the steering committee of the BX workshop series (since 2012) which represents the area of bidirectional transformation research. This seminar aims to be broad; the guest list contains new faces from the bidirectional transformation and neighbouring research communities, as well as long-term contributors in this area. Further information is available at:

http://bx-community.wikidot.com/.

The four-day meeting is the best fit for us; specifically, we plan to include:

• Summaries of recent research in each field given by selected invitees/organisers
• Talks from invitees, to suggest new ideas and challenges and to present ongoing research works
• Intra-community discussion to identify potential collaborations and select topics from previous talks

• Inter-community group discussions (participants divided into sub-groups to discuss specific challenges or new topics)

• Wrap-up discussions

We expect that invited experts from different fields will bring new ideas and perspectives, which will lead to further collaboration and new research results. We strongly believe this will happen, as we have been successful in the previous four BX meetings listed above. The report that we will prepare to summarise the discussions will showcase challenges in the field and serve as a good entry point for newcomers in this area.