6th International Workshop on Reaction Systems

Important dates

• Abstract submission: April 15, 2026

• Workshop: TBA (June 23 or June 26)

• Main conference UCNC 2026: June 22-26, 2026

About the workshop

The 6th edition of the Reaction Systems Workshop takes place at the University of Trieste, Italy on June 2N, 2026. The workshop is planned as an on-site/in-person full day event. It is co-located with the 23rd International Conference on Unconventional Computing and Natural Computing UCNC 2026, which features a broad and stimulating scientific program, including topics such as self-organizing robot swarms, molecular self-assembly, and cellular automata.  

Since their introduction nearly 20 years ago, reaction systems have evolved into a broad inter-disciplinary research area, driven by both biological motivations as well as the need to understand interactive computation. Research in this field is extensive and diverse, spanning theoretical foundations, applications and software tools. It encompasses various types of reaction systems, their mathematical properties, and their connections to other fields.  In response to the growing interest, a series of workshops and schools on reaction systems has been established to present state-of-the-art developments, exchanging research ideas, foster new collaborations, and strengthen existing ones.

Previous editions of the workshop: 

• Fifth edition: Nice, France, September 2025

• Fourth edition: Pisa, Italy, September 2024.

• Third edition: Jacksonville, Florida, USA, March 2023. 

• Second edition: Torun, Poland, June 2019. 

• First edition: Milano, Italy, June 2018. 

Main organizers of the 2026 edition: Luca Manzoni (University of Trieste, Italy) and Ion Petre (University of Turku, Finland)

Invited speakers

• Paolo Bottoni, Department of Computer Science, Sapienza University of Rome, Italy

Title: Nature vs. Nurture: When environment matters

Abstract

The classical model of reaction systems sees the environment as an undifferentiated source of context contributions complementing the products of internal reactions of a system, where the environment and the system share a common background set. A natural development is the consideration of different kinds of constraint on the possible contributions. Since the inception of the notion of interactive processes in reaction systems, context-independent processes have been defined as those in which the environment only produces entities already present in the state of the system as product of its reactions. The search for families of processes genuinely intermediate between context-independent and arbitrary ones, as well as for processes computing specific functions has therefore led to investigating the effect of different constraints on the possible environmental contributions. The  talk will provide an overview of some of such models. In particular, it will consider: functional environments (where contributions depend on products of previous reactions); structured environments (where some spatially distributed collection of reaction systems provide contributions for one another); restrictions on the sets of entities that the environment can contribute (up to establishing a self / non-self partition of the entities in the background set, where the environment can only contribute entities that the system cannot produce on its own). Finally, a novel model of system based on the distinction between enablers and inhibitors will be presented, where the environment plays an active and determining role in the construction of the product of internal reactions.

Short bio

Paolo Bottoni is Full Professor of Computer Science at Sapienza University. His research interests are in formal methods for model-driven development, in multimedia applications, and in the modelling of interactive processes. In particular, he has worked on the formal definition of annotation systems, the compositional generation of specifications from patterns, and the specification of verification of contracts and policies under different approaches to formal modeling. Author of more than 230 publications, he has participated in several national and international projects. He serves, or has served, as member of numerous international program committees, of the Steering Committee of various international conferences and of the Editorial Board of international journals. He has acted as editor of special issues of international journals and has also promoted workshops on topics modelling and development of diagrammatic languages for software engineering and Human Computer Interaction. He is among the founders of the University startup BB-SMILE, aimed at developing solutions based on blockchain technology to ensure transparency, traceability and security in processes.

• Linda Brodo, University of Sassari, Italy

Title: When Reactions meet Processes: a flexible compositional framework

Abstract

After a brief introduction to classical Reaction Systems (RS), we present their process-algebraic semantics. We adopt structural operational semantics (SOS) while preserving the original RS dynamics. The computational nature of SOS, however, enables us to extend the expressive power of RS by introducing additional computational features. In this framework, the context is modeled as a parallel process that may exhibit non-deterministic and recursive behavior and can be equipped with additional actions. This extension provides a flexible modeling framework suitable for a variety of domains, including systems biology, medical therapies, and market dynamics. Moreover, it enables the use of well-established analysis techniques from process algebra. These ideas are implemented in BioResolve, a Prolog-based tool that supports the extended RS framework. The system remains backward compatible with classical RS, as the original dynamics can be recovered by disabling the additional features. We also discuss an implementation in Maude, supporting recursion and non-determinism, which allows efficient execution of large case studies and enables the use of model-checking techniques available in the Maude environment.

Short bio

Linda Brodo is Associate Professor of Computer Science at the University of Sassari. Her research focuses on formal methods for modeling and analyzing complex systems. In particular, she studies abstract parallel programming languages for the specification and verification of distributed systems, using theoretical frameworks such as process algebras and rewriting systems. The formal rigor and expressive power of these methods enable the analysis of systems across a wide range of application domains. She has published widely in international journals and conferences in the area of formal methods and distributed systems.

Program

• TBA

Call for contributed talks

We welcome talks on all aspects of reaction systems, including, but not limited to: 

• new variants of reaction systems; 

• mathematical and computational properties of reaction systems; 

• biological aspects of reaction systems;

• relationships to other areas;

• software tools;

• applications and case-studies. 

Talks may present novel, unpublished research results as well as research published in peer-reviewed journals and conferences since 2024. To propose a talk, send an email to ion.petre@utu.fi with an extended abstract (up to 2 pages). If the proposal is based on an already published article, include the bibliographical reference in the proposal. 

 The workshop will not publish a proceedings volume. A special issue based on the workshop is planned to be organized in Natural Computing. A separate call for novel, unpublished research will be issued, and submissions will undergo a separate peer-review process.

Submission deadline: March 31, 2026.

Organizers

• Luca Manzoni, University of Trieste, Italy

• Ion Petre, University of Turku, Finland and National Institute of R&D for Biological Sciences, Romania (chair)