Local reversibility in a Calculus of Covalent Bonding

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.We introduce a process calculus with a new prefixing operator that allows us to model locally controlled reversibility. Actions can be undone spontaneously, as in other reversible process calculi, or as pairs of concerted actions, where performing a weak action forces undoing of another action. The new operator in its full generality allows us to model out-of-causal order computation, where causes are undone before their effects are undone, which goes beyond what typical reversible calculi can express. However, the core calculus, which uses only the reduced form of the new operator, is well behaved as it satisfied causal consistency. We demonstrate the usefulness of the calculus by modelling the hydration of formaldehyde in water into methanediol, an industrially important reaction, where the creation and breaking of some bonds are examples of locally controlled out-of-causal order computation

Reversibility and asymmetric conflict in event structures

Reversible computation has attracted increasing interest in recent years, with applications in hardware, software and biochemistry. We introduce reversible forms of prime event structures and asymmetric event structures. In order to control the manner in which events are reversed, we use asymmetric conflict on events. We prove a number of results about reachable configurations; for instance, we show under what conditions reachable configurations which are finite are reachable by purely finite means. We discuss, with examples, reversing in causal order, where an event is only reversed once all events it caused have been reversed, as well as forms of non-causal reversing

Reversing place transition nets

Petri nets are a well-known model of concurrency and provide an ideal setting for the study of fundamental aspects in concurrent systems. Despite their simplicity, they still lack a satisfactory causally reversible semantics. We develop such semantics for Place/Transitions Petri nets (P/T nets) based on two observations. Firstly, a net that explicitly expresses causality and conflict among events, for example an occurrence net, can be straightforwardly reversed by adding a reverse transition for each of its forward transitions. Secondly, given a P/T net the standard unfolding construction associates with it an occurrence net that preserves all of its computation. Consequently, the reversible semantics of a P/T net can be obtained as the reversible semantics of its unfolding. We show that such reversible behaviour can be expressed as a finite net whose tokens are coloured by causal histories. Colours in our encoding resemble the causal memories that are typical in reversible process calculi.Fil: Melgratti, Hernan Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigación en Ciencias de la Computación. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigación en Ciencias de la Computación; ArgentinaFil: Mezzina, Claudio Antares. Università Degli Studi Di Urbino Carlo Bo; ItaliaFil: Ulidowski, And Irek. University of Leicester; Reino Unid

Reversible Execution for Robustness in Embodied AI and Industrial Robots

International audienceReversible computation is a computing paradigm where execution can progress backwards as well as in the usual, forward direction. It has found applications in many areas of computer science, such as circuit design, programming languages, simulation, modelling of chemical reactions, debugging and robotics. In this article, we give an overview of reversible computation focusing on its use in robotics. We present an example of programming industrial robots for assembly operations where we combine classical AI planning with reversibility and embodied AI to increase robustness and versatility of industrial robots

Semantics and expressiveness of ordered SOS

AbstractStructured Operational Semantics (SOS) is a popular method for defining semantics by means of transition rules. An important feature of SOS rules is negative premises, which are crucial in the definitions of such phenomena as priority mechanisms and time-outs. However, the inclusion of negative premises in SOS rules also introduces doubts as to the preferred meaning of SOS specifications.Orderings on SOS rules were proposed by Phillips and Ulidowski as an alternative to negative premises. Apart from the definition of the semantics of positive GSOS rules with orderings, the meaning of more general types of SOS rules with orderings has not been studied hitherto. This paper presents several candidates for the meaning of general SOS rules with orderings and discusses their conformance to our intuition for such rules.We take two general frameworks (rule formats) for SOS with negative premises and SOS with orderings, and present semantics-preserving translations between them with respect to our preferred notion of semantics. Thanks to our semantics-preserving translation, we take existing congruence meta-results for strong bisimilarity from the setting of SOS with negative premises into the setting of SOS with orderings. We further compare the expressiveness of rule formats for SOS with orderings and SOS with negative premises. The paper contains also many examples that illustrate the benefits of SOS with orderings and the properties of the presented definitions of meaning

Reversible Computing in Debugging of Erlang Programs

International audienceReversible computation is a computing paradigm where execution can progress backwards as well as in the usual, forward direction. It has found applications in many areas of computer science, such as circuit design, programming languages, simulation, modelling of biochemical reactions, debugging and robotics. In this article, we give an overview of reversible computation focusing on its use in reversible debugging of concurrent programs written in the Erlang programming language

An Axiomatic Approach to Reversible Computation

Undoing computations of a concurrent system is beneficial inmany situations, e.g., in reversible debugging of multi-threaded programsand in recovery from errors due to optimistic execution in parallel dis-crete event simulation. A number of approaches have been proposed forhow to reverse formal models of concurrent computation including pro-cess calculi such as CCS, languages like Erlang, prime eventstructuresand occurrence nets. However it has not been settled what properties areversible system should enjoy, nor how the various properties that havebeen suggested, such as the parabolic lemma and the causal-consistencyproperty, are related. We contribute to a solution to these issues by usinga generic labelled transition system equipped with a relationcapturingwhether transitions are independent to explore the implications betweenthese properties. In particular, we show how they are derivable from aset of axioms. Our intention is that when establishing properties of someformalism it will be easier to verify the axioms rather than proving prop-erties such as the parabolic lemma directly. We also introduce two newnotions related to causal consistent reversibility, namely causal safetyand causal liveness, and show that they are derivable from our axioms