Transactions and contracts based on reaction systems

Abstract Smart contracts are currently en vogue, thanks to the infrastructure provided by the blockchain technology. However, their effective use requires that the textual (legalese) specification of the contract be accompanied by a precise computational definition of the actions leading to its satisfaction or breach, as well as of their admissible sequences. Insofar as contracts can be viewed as prescribing transactional exchanges of well-specified resources among well-specified actors, contract execution can be modelled as following some protocol in a closed world. This suggests a modelling of such executions as interactive processes in reaction systems, where the entities in the background set represent possible allocations of resources to actors and reactions describe changes in such allocations. We use this type of reaction systems and interactive processes as a basis for the modelling of transactions and contracts and explore properties of such processes, highlighting their peculiarities with respect to the original notion of interactive processes in reaction systems. We also discuss several constructions for composition and decomposition of processes, which guarantee equivalence of effects: two interactive processes are equivalent if, starting from the same initial set of allocations, they produce the same final set of allocations.