Abstract We propose an extension to the framework of reaction systems such that the environment not only plays the role of contributing entities to the successor state, but also influences the actual generation of products. In particular, we consider that an environment can assign valences to entities, be they used as reactants or inhibitors in a reaction, as well as select the entities which can appear in the successor state as product of a reaction. This provides a framework for immersing reaction system specifications into different contexts. We also derive a notion of polarised reaction systems , where entities can appear only as reactants or inhibitors in any given reaction. We compare the expressive power of the models, also showing some equivalences between them, and test them on three case studies derived from physiology, ecology, and chemistry.

Abstract We proceed in the investigation of models of environment in reaction systems, beyond the simple models establishing context-independent or arbitrary processes, to consider restrictions on both the sets of entities that an environment can contribute to a reaction system and the set of entities that a reaction system can produce. Such a distinction is reminiscent of that between self and non-self in living systems and is examined in this paper under different respects. We discuss applications of the model to living systems and security, as well as relations between families of reaction systems with self distinction, unveiling peculiarities of processes with self distinction with respect to the classical notion, for both context-independent processes and processes with arbitrary context. In particular, we introduce a notion of simulation, through which we show that the restriction to systems with self distinction does not entail any loss in the set of realisable behaviours, and that there exists a family of reaction systems with self distinction able to simulate context-independent behaviours of classical reaction systems through processes with arbitrary context. Moreover, using 2-step simulations, we show that every reaction system with self distinction can be reduced to a system (with self-distinction) using only reactions where no set of reactants and inhibitors mixes entities from both the self and the non-self sets.

A key component of blockchain technology is the ledger, viz., a database that, unlike standard databases, keeps in memory the complete history of past transactions as in a notarial archive for the benefit of any future test. In second-generation blockchains such as Ethereum, the ledger is coupled with smart contracts, which enable the automation of transactions associated with agreements between the parties of a financial or commercial nature. The coupling of smart contracts and ledgers provides the technological background for very innovative application areas, such as Decentralized Autonomous Organizations (DAOs), Initial Coin Offerings (ICOs), and Decentralized Finance (DeFi), which propelled blockchains beyond cryptocurrencies that were the only focus of first generation blockchains, such as Bitcoin. However, the currently used implementation of smart contracts as arbitrary programming constructs has made them susceptible to dangerous bugs that can be exploited maliciously and has moved their semantics away from that of legal contracts. We propose here to recompose the split and recover the reliability of databases by formalizing a notion of contract modeled as a finite-state automaton with well-defined computational characteristics derived from encoding in terms of allocations of resources to actors, as an alternative to the approach based on programming. To complete the work, we use temporal logic as the basis for an abstract query language that is effectively suited to the historical nature of the information kept in the ledger.

The study of algebraic modelling of labelled non-deterministic concurrent processes leads us to consider a categoryLB, obtained from a complete meet-semilatticeBand fromB-valued equivalence relations. We prove that, ifBhas enough properties, thenLBpresents a two-fold internal logical structure, induced by two doctrines definable on it: one related to its families of subobjects and one to its families of regular subobjects. The first doctrine is Heyting and makesLBa Heyting category, the second one is Boolean. We will see that the difference between these two logical structures, namely the different behaviour of the negation operator, can be interpreted in terms of a distinction between non-deterministic and deterministic behaviours of agents able to perform computations in the context of the same process. Moreover, the sorted first-order logic naturally associated withLBcan be extended to a modal/temporal logic, again using the doctrinal setting. Relations are also drawn to other computational models.

We extend the study of networks of evolutionary processors accepting words to a similar model, processing rectangular pictures. To this aim, we introduce accepting networks of evolutionary picture processors and investigate their computational power. We show that these networks can accept the complement of any local picture language as well as picture languages that are not recognizable. Some open problems regarding decidability issues and closure properties are finally discussed.

In the proposed demo, a new approach to e-learning environments for deaf people is illustrated. Using a fully iconic web-based environment, a tutor can define, generate and test e-learning courses for deaf people, which are automatically managed, published and served by the system itself.

We study the functorial characterisation of bisimulation-based equivalences over a categorical model of labelled trees. We show that in a setting where all labels are visible, strong bisimilarity can be characterised in terms of enriched functors by relying on the reflection of paths with their factorisations. For an enriched functor F, this notion requires that a path (an internal morphism in our framework) π going from F(A) to C corresponds to a path p going from A to K, with F(K) = C, such that every possible factorisation of π can be lifted in an appropriate factorisation of p. This last property corresponds to a Conduché property for enriched functors, and a very rigid formulation of it has been used by Lawvere to characterise the determinacy of physical systems. We also consider the setting where some labels are not visible, and provide characterisations for weak and branching bisimilarity. Both equivalences are still characterised in terms of enriched functors that reflect paths with their factorisations: for branching bisimilarity, the property is the same as the one used to characterise strong bisimilarity when all labels are visible; for weak bisimilarity, a weaker form of path factorisation lifting is needed. This fact can be seen as evidence that strong and branching bisimilarity are strictly related and that, unlike weak bisimilarity, they preserve process determinacy in the sense of Milner.

Current research in interaction aims at defining new types of multimedia and multimodal experience, at enriching everyday objects and environments with the ability to capture user actions and intentions, and at integrating real and virtual sources of information, typically exploiting the visual channel. These forms of interaction usually require dedicated architectures, often relying on different component models, and with rigid types of configuration. We present an approach to the integration of real and virtual world sensors and effectors, and of traditional multimedia environments within a single component-based architecture. Environments in this architecture are defined as networks of plugins, each equipped with computational, presentation and communication capabilities. Examples of integrated environments produceable with this architecture are given.

The use of the Web and the diffusion of knowledge management systems makes it possible to base discussions upon a vast set of documents, many of which also include links to multimedia material, such as images or videos. This perspective could be exploited by allowing a team to collaborate by exchanging and retrieving annotated multimedia documents (text, images, audio and video). We designed and developed a digital annotation system, MADCOW, to assist users in constructing, disseminating, and retrieving multimedia annotations of documents, supporting collaborative activities to build a web of decision-related documents. We made a strong effort in designing the user interface and we tested it with 24 users. We describe a scenario in which annotation plays a crucial role, where the object of the collaboration is a politically and artistically important palace of Rome, for which the availability of images and historical documentation is fundamental in order to take informed decisions. We demonstrate the MADCOW interface and its use in the restoration team. The annotations can be used to support teamwork as well as to offer the public some reasoned integration and guide to the available material.

We present HYPERSCORE, a system for interactive execution of musical performances coupled with the generation system CLIPSCORE, in which a performer can virtually manipulate execution parameters through gestural interaction in real time. HYPERSCORE allows users to exploit their perceptive capabilities in terms of space and time in order to control and manipulate, via a multimodal interaction, the main component of music, namely time.

We provide a finite equational axiomatization for bisimulation equivalence of nondeterministic interpretation of regular expressions. Our axiomatization is heavily based on the one by Salomaa, that provided an implicative axiomatization for a large subset of regular expressions, namely all those that satisfy the non-empty word property (i.e. without 1 summands at the top level) in *-contexts. Our restriction is similar, it essentially amounts to recursively requiring that the non-empty word property be satisfied not just at top level but at any depth. We also discuss the impact on the axiomatization of different interpretations of the 0 term, interpreted either as a null process or as a deadlock.