Synchronous Language

The development and authoring of interactive music or applications , such as user interfaces for arts & exhibitions has traditionally been done with tools that pertain to two broad metaphors. Cue-based environments work by making groups of parameters and sending them to remote devices , while more interactive applications are generally written in generic art-oriented programming environments, such as Max/MSP, Processing or openFrameworks. In this paper, we present the current version of the i-score se-quencer. It is an extensive graphical software that bridges the gap between time-based, logic-based and flow-based interactive application authoring tools. Built upon a few simple and novel primitives that give to the composer the expressive power of structured programming, i-score provides a time line adapted to the notation of parameter-oriented interactive music, and allows temporal scripting using JavaScript. We present the usage of these primitives, as well as an i-score example o...

Annotated multilayer data approaches are becoming widespread in historical corpora. In this context, the Tycho Brahe Corpus of Historical Portuguese was the pioneer in this approach and several other initiatives emerged based on its annotation, generated by e-Dictor software. During the research conducted with corpora based on this annotation scheme, some gaps were identified to cater to the requirements for manuscript sources and conformity increase using annotation standards. These requirements include the TEI (Text Encoding Initiative) Guidelines, which provide a standard format for encoding of texts, to achieve more interoperability, while at the same time solving problems of missing adequacy in the current encoding, among others. This work presents an annotation scheme proposal for the philological editions (or editorial interventions) and morphological analyses of Portuguese historical corpus encoded by XML (eXchange Markup Language). The presented encoding scheme fulfills the reliability requirement for this kind of corpora while achieving more adequacy, conformity, and, consequently, more interoperability.

This paper discusses fundamentals of hybrid system modelling. Emphazis is put on compositionality and the use of multiform time. Compositionality refers to the ability of freely composing hybrid systems. Since hybrid systems are considered, different time indices occur, and modularity calls for considering "time" as local to each module, this is what is called multiform time. The proposed framework is behavioral, hence a way is provided to automatically synthesize proper scheduling constraints for the joint simulation of discrete time, event based, and continuous time components. Finally, the relations of this model with the more traditional state based point of view are discussed.

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There are important distributed computing systems which are neither massive nor high performance. Examples are: telecommunications systems, transportation or power networks, embedded control systems (such as embedded electronics in automobiles), or Systems on a Chip. Many of them are embedded systems, i.e., not directly visible to the user. For these systems, performance is not a primary issue, major issues are reviewed in this paper. Then, we focus on a particular but important point, namely the correct implementation of specifications on distributed architectures.

software projects using Simulink or Scade use in fact a subset of Simulink or Scade. The 'alignment' of these two subsets gives rise to a new concept, the 'Unified MBD', whose data-flow part keeps the expressiveness of both languages and has been introduced in a former paper. Here we present the control-flow part, which is much more restrictive, because the automata paradigms of Scade and Simulink differ fundamentally. But in fact, at least in our context, this loss of expressiveness is not a weakness, because our current design modelling practice is consistent with these restrictions, and because it opens the road for simple but faithful specification modelling practices.

Architecture description languages are used to describe both the hardware and software architecture of an application, at system-level. The basic software components are intended to be developed independently, and then deployed on the described architecture. This separate development of the architecture and of the software raises the problem of early validation of the integrated system. In this paper, we propose to solve this problem by translating the architecture into an executable model, which can be simulated and validated together with the software components. More specifically, we consider the case where the architecture is described in the AADL language, and the software components are developed in some synchronous language like Scade or Lustre. We show how the architecture can be automatically translated into a non-deterministic synchronous model, to which the actual software component can be integrated. The result is an executable integrated synchronous model, which can be validated with tools available for synchronous programs. The approach is illustrated on an industrial case study extracted from an actual spatial system.

en français Nous présentons l'étude d'un corpus de séances de rétrospection collective menées suite à du tutorat en ligne qui associe un apprenti-enseignant et deux apprenants de français à travers une plate-forme de visio-conférence. Nous voyons comment la tension entre respect du contrat pédagogique et valorisation de la prise d'initiative de l'apprenant traduit une instabilité autour du concept didactique de "conversation pédagogique", que nous proposons de dépasser à l'aide de l'entrée par la gestion de l'imprévu dans une appréhension postdualiste de l'interaction pédagogique. We present the study of a corpus of collective retrospection sessions undertaken after online tutoring, in which a trainee teacher is paired with two learners of French, through a visioconference platform. We see how the tension between respecting the pedagogical contract and valorizing the learner's initiative is a sign of instability around the didactical concept of "pedagogical conversation", which we propose to overcome through an approach around the handling of the unexpected, in a postdualist apprehension of the pedagogical interaction.

Consider the problem to design a component that combined with a known part of a system, called the context, conforms to a given overall specification. This question arises in several applications ranging from logic synthesis to the design of discrete controllers. We cast the problem as solving abstract equations over languages. As part of an ongoing research project we already defined language equations with respect to two language composition operators: synchronous composition,, and parallel composition,¥; conformity ...

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We present a tool for the design and validation of embedded real-time applications. The tool integrates two approaches, the use of the synchronous programming language ESTEREL for design and the application of model-checking techniques for validation of real-time properties. Validation is carried out on a global formal model (timed automata) taking into account the effective implementation of the application on the target hardware architecture as well as its external environment behavior.

Learning a second language at a distance poses a tremendous challenge to learners. Physical distance from teachers and peers coupled with possible isolation from the relevant language community makes language learning extremely difficult. However, live interaction supported by synchronous learning management systems (SLMS) over the Internet holds great potential to address various difficulties facing distance language learners. By allowing students and instructors to negotiate linguistic issues together in real-time virtual settings, ...

There exists many ways to connect two, three or more neurons together to form different graphs. We call archetypes only the graphs whose properties can be associated with specific classes of biologically relevant structures and behaviors. These archetypes are supposed to be the basis of typical instances of neuronal information processing. To model different representative archetypes and express their temporal properties, we use a synchronous programming language dedicated to reactive systems (Lustre). The properties are then automatically validated thanks to several model checkers supporting data types. The respective results are compared and depend on their underlying abstraction methods.

A service robot especially a care-providing robot, works in the vicinity of a human body and is sometimes even in direct contact with it. Conventional safety methods and precautions in industrial robotics are not applicable to such robots. This paper presents a safety approach for designing the safe care-providing robot FRIEND. The approach is applied in each step of design iteratively to identify and assess the potential hazards during design. The steps are explained briefly in this work. The main contribution of this paper is verification of safety requirements using the Ramadge-Wonham (RW) framework. The greater complexity of the tasks the robot will perform, the more complex is the identification of safety requirements. Use of this framework led us to analyze the requirements and verify them formally, systematically and on a modular basis. In our approach human-robot interaction (HRI) is also modeled by a set of uncontrolled events that may happen any time during operation. Subsequently the safety requirements are modified to consider these interactions. As a result the safety module behaves like a controller, running in parallel with the system, which maintains the system safe and works according to the safety requirements by enabling the admissible sequences of events.

The compilation of Esterel into software has mainly targeted uniprocessor execution. The inherent parallelism of the original description would typically have to be compiled away in order for it to be executed sequentially on a processor. This paper proposes a new compilation scheme that would be able to compile Esterel for distributed execution. This method enables the parallelism of the original description to be realised through actual concurrent execution on multiple processors, or through sequentialized concurrency within a single processor. Both these forms of concurrency can be mixed together for a given implementation. Experimental results indicate significant speed-ups in the performance of concurrently executed distributed programs compared to software implementations on a uniprocessor. When the prototype compiler is used to compile for just a single processor, results show that its performance is comparable to other simulation-based compilers, and significantly faster compared to gate-based compilers, especially for large programs.

Lurette is an automated testing tool dedicated to reactive programs. The test process is automated at two levels: given a formal description of the System Under Test (SUT) environment, Lurette generates realistic input sequences; and, given a formal description of expected properties, Lurette performs the test results analysis. Lurette has been reimplemented from scratch. In this new version, the main novelty lies in the way the SUT environment is described. This is done by means of a new dedicated language called Lucky, a language for programming nondeterministic reactive machines. This article recalls the principles of Lurette, briefly presents the Lucky language, and describes some cases studies from the IST project Safeair II. The objective is to illustrate the usefulness of Lurette on real case studies, and the expressiveness of Lucky in accurately describing the SUT environment.

Consider the problem of designing a component that combined with a known part of a system, called the context, conforms to a given overall specification. This question arises in several applications ranging from logic synthesis to the design of discrete controllers. We cast the problem as solving abstract equations over languages and study the most general solutions under the synchronous and parallel composition operators. We also specialize such language equations to languages associated with important classes of automata used for modeling ...

We present the HistCorp collection, a freely available open platform aiming at the distribution of a wide range of historical corpora and other useful resources and tools for researchers and scholars interested in the study of historical texts. The platform contains a monitoring corpus of historical texts from various time periods and genres for 14 European languages. The collection is taken from well-documented historical corpora, and distributed in a uniform, standardised format. The texts are downloadable as plaintext, and in a tokenised format. Furthermore, a subset of the corpus contains information on the modern spelling variant, and some of the texts are also annotated with part-of-speech and syntactic structure. In addition, preconfigured n-gram language models and spelling normalisation tools are provided to allow the study of historical languages.

Hybrid systems exhibit mode-dependent continuous-time dynamics. They are encountered in several phases of Cyber-Physical Systems design: physical system modeling, budgeting time over the computing architecture, safety analyses, and more generally virtual system modeling. These different phases typically involve different kinds of tools, with differing interpretations of the underlying mathematics. By exhibiting a mix of continuous-and discrete-time, hybrid systems raise a number of unexpected challenges for existing modeling and simulation tools. We review these challenges and propose some new perspectives for addressing them. Recalling the theoretical effort that underpinned the development of synchronous languages-which allowed, for example, the development of a certified compiler for SCADE-we propose redoing the same for hybrid systems modeling tools.

A fundamental asset of a model-based development process is the capability of providing an automatic implementation of the model that preserves its semantics, and at the same time makes efficient use of the execution platform resources. Synchronous Reactive (SR) models are increasingly used in model-based design flows for the development of embedded control applications. The implementation of communication links between functional blocks in an SR model requires buffering schemes and access procedures implemented at the kernel level. Platform-based design methodology is introduced to synthesize a real-time operating system when implementing SR models. Previous research has proposed two methods for sizing the communication buffer. This dissertation demonstrates how it is possible to improve on the

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Interactive scores proposes a model to write and execute interactive multimedia scores. The software I-SCORE implements the above model using Hierarchical Time Stream Petri Nets (HTSPN). However, this model is very static and modelling new features would require a complete redesign of the network or sometimes they cannot be expressed. Another problem of I-SCORE is that it does not provide a good visual feedback of the execution of the scenario. In this work, we define and implement an interpreter of interactive scores using the synchronous pro- gramming language REACTIVEML. Our work takes advantage of the expressiveness of the reactive model and the power of functional programming to develop an interpreter more dynamic and simple. Contrary to the Petri Net model, our approach allows to model precisely the hierarchical behaviour, and permits the easy prototyping of new features. We also propose a visualization system using the environment INSCORE that provides a real-time visualizati...

Interactive Scores (IS) is a formalism for composing and performing interactive multimedia scores with several applications in video games, live performance installations, and virtual museums. The composer defines the temporal organization of the score by asserting temporal relations (TRs) between temporal objects (TOs). At execution time, the performer may modify the start/stop times of the TOs by triggering interaction points and the system guarantees that all the TRs are satisfied. Implementations of IS and formal models of their behavior have already been proposed, but these do not provide usable means to reason about their properties. In this paper we introduce ReactiveIS, a programming language that fully captures the temporal structure of IS during both composition and execution. For that, we propose a semantics based on tree-like structures representing the execution state of the score at each point in time. The semantics captures the hierarchical aspects of IS and provides an intuitive representation of their execution. We also endow ReactiveIS with a logical semantics based on linear logic, thus widening the reasoning techniques available for IS. We show that ReactiveIS is general enough to capture the full behavior of IS and it also provides declarative ways to increase the expressivity of IS with, for instance, conditional statements and loops.

The paper addresses the problem of solving equations over languages, that model the problem of synthesizing an unknown component, both in hardware and software systems. We investigate what algebraic properties must be satisfied by a composition operator so that the related language equation yields a general solution of the same form, and show sufficient conditions to derive such a largest solution from which the solutions of synchronous and parallel equations follow as special cases. The second contribution is a ...

Lurette is an automated testing tool dedicated to reactive programs. The test process is automated at two levels: given a formal description of the System Under Test (SUT) environment, Lurette generates realistic input sequences; and, given a formal description of expected properties, Lurette performs the test results analysis. Lurette has been reimplemented from scratch. In this new version, the main novelty lies in the way the SUT environment is described. This is done by means of a new dedicated language called Lucky, a language for programming nondeterministic reactive machines. This article recalls the principles of Lurette, briefly presents the Lucky language, and describes some cases studies from the IST project Safeair II. The objective is to illustrate the usefulness of Lurette on real case studies, and the expressiveness of Lucky in accurately describing the SUT environment.

The workshops on Synchronous Languages started in 1993 at Schloss Dagstuhl. Since then seven such workshops have been organized, in total: 2 in Germany, 1 in Spain, and 4 in France, with an attendance varying between 40 and 60 persons. In 1993 the synchronous languages approach was promising: numerous design tools had been, or were in train of being, constructed based on the languages ESTEREL (Berry), Lustre (Halbwachs, Caspi), Signal (LeGuernic, Benveniste), and Statecharts (Harel, Pnueli), and were applied to the design of control of (real-time) embedded systems. Now, in 2000/2001, this approach is established, and possibly even more essential to computer science than the well-known model-checking paradigm to automatic verification. The software for the Airbus 340 has been entirely designed using the SCADE tool, based on a graphical representation of Lustre; the software for the Airbus 385 is being designed, based on SCADE; the software for the Rafale fighter bomber by Dassault — ...

In their seminal 1991 paper "What is in a Step: On the Semantics of Statecharts", Pnueli and Shalev showed how, in the presence of global consistency and while observing causality, the synchronous language Statecharts can be given coinciding operational and declarative step semantics. Over the past decade, this semantics has been supplemented with order-theoretic, denotational, axiomatic and game-theoretic characterisations, thus revealing itself as a rather canonical interpretation of the synchrony hypothesis. In this paper, we survey these characterisations and use them to emphasise the close but not widely known relations of Statecharts to the synchronous language Esterel and to the field of logic programming. Additionally, we highlight some early reminiscences on Amir Pnueli's contributions to characterise the semantics of Statecharts.

Interactive Scores (IS) are a formalism for the design and performance of interactive multimedia scenarios. IS provide temporal relations (TR), but they cannot represent conditional branching and TRs simultaneously. We propose an extension to Allombert et al.'s IS model by including a condition on the TRs. We found out that in order to have a coherent model in all possible scenarios, durations must be flexible; however, sometimes it is possible to have fixed durations. To show the relevance of our model, we modeled an existing multimedia installation called Mariona. In Mariona there is choice, random durations and loops. Whether we can represent all the TRs available in Allombert et al.'s model into ours, or we have to choose between a timed conditional branching model and a pure temporal model before writing a scenario, still remains as an open question.

A compositional method is presented for the verification of multi-agent systems. The advantages of the method are the well-structuredness of the proofs and the reusability of parts of these proofs in relation to reuse of components. The method is illustrated for an example multi-agent system, consisting of cooperative information gathering agents. This application of the verification method results in a formal analysis of pro-activeness and reactiveness of agents, and shows which combinations of pro-activeness and reactiveness in a specific type of information agents lead to a successful cooperation.. * An earlier version of this paper was presented at the International Workshop on Compositionality, COMPOS'97; see (Jonker and Treur, 1998). • process composition, • knowledge composition, • the relation between process composition and knowledge composition. These three types of knowledge are discussed in more detail below. 2.1 Process Composition Process composition identifies the relevant processes at different levels of (process) abstraction, and describes how a process can be defined in terms of lower level processes. 2.1.1 Processes at Different Levels of Abstraction Processes can be described at different levels of abstraction; for example, the process of the multiagent system as a whole, processes defined by individual agents and the external world, and processes defined by task-related components of individual agents. Specification of a Process The identified processes are modelled as components. For each process the types of information required as input and resulting as output are identified as well. This is modelled as input and output interfaces of the components.

Dataflow programming languages are used in a variety of settings, and defects in their programs can have serious consequences. However, prior work in automated program repair (APR) emphasizes control flow over dataflow languages. We identify three impediments to the use of APR in dataflow programming-parallelism, state, and evaluation-and highlight opportunities for overcoming them.

SIGNAL is a part of the synchronous languages family, which are broadly used in the design of safety-critical real-time systems such as avionics, space systems, and nuclear power plants. There exist several semantics for SIGNAL , such as denotational semantics based on traces (called trace semantics), denotational semantics based on tags (called tagged model semantics), operational semantics presented by structural style through an inductive definition of the set of possible transitions, operational semantics defined by synchronous transition systems(STS), etc. However, there is little research about the equivalence between these semantics. In this work, we would like to prove the equivalence between the trace semantics and the tagged model semantics, to get a determined and precise semantics of the SIGNAL language. These two semantics have several different definitions respectively, we select appropriate ones and mechanize them in the Coq platform, the Coq expressions of the abstract syntax of SIGNAL and the two semantics domains, i.e., the trace model and the tagged model, are also given. The distance between these two semantics discourages a direct proof of equivalence. Instead, we transform them to an intermediate model, which mixes the features of both the trace semantics and the tagged model semantics. Finally, we get a determined and precise semantics of SIGNAL.

SIGNAL is a part of the synchronous languages family, which are broadly used in the design of safety-critical real-time systems such as avionics, space systems, and nuclear power plants. There exist several semantics for SIGNAL , such as denotational semantics based on traces (called trace semantics), denotational semantics based on tags (called tagged model semantics), operational semantics presented by structural style through an inductive definition of the set of possible transitions, operational semantics defined by synchronous transition systems(STS), etc. However, there is little research about the equivalence between these semantics. In this work, we would like to prove the equivalence between the trace semantics and the tagged model semantics, to get a determined and precise semantics of the SIGNAL language. These two semantics have several different definitions respectively, we select appropriate ones and mechanize them in the Coq platform, the Coq expressions of the abstract syntax of SIGNAL and the two semantics domains, i.e., the trace model and the tagged model, are also given. The distance between these two semantics discourages a direct proof of equivalence. Instead, we transform them to an intermediate model, which mixes the features of both the trace semantics and the tagged model semantics. Finally, we get a determined and precise semantics of SIGNAL.

In this paper, we present a parallel programming and execution model based on a logical ordering of control ows. We show that it is possible to provide a unifying framework consisting of a synchronous programming model, thereby enabling sequential program reading, and an asynchronous execution model yielding e cient executions. Our approach is based on a SPMD and task parallel programming language, called SCL ? Chan. Communications take place through channels and rely on explicit send/receive instructions. In opposite to classical message passing models, synchronizations and communications are dissociated. We show that it is possible to perform a data-driven automatic translation of sequential arbitrary DOACROSS loops into SCL ? Chan by using non-matching send/receive instructions. Our parallelization technique handles irregular control leading to optimizations of communications in irregular computations.

In this paper, we present a parallel programming and execution model based on a logical ordering of control ows. We show that it is possible to provide a unifying framework consisting of a synchronous programming model, thereby enabling sequential program reading, and an asynchronous execution model yielding e cient executions. Our approach is based on a SPMD and task parallel programming language, called SCL ? Chan. Communications take place through channels and rely on explicit send/receive instructions. In opposite to classical message passing models, synchronizations and communications are dissociated. We show that it is possible to perform a data-driven automatic translation of sequential arbitrary DOACROSS loops into SCL ? Chan by using non-matching send/receive instructions. Our parallelization technique handles irregular control leading to optimizations of communications in irregular computations.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

In this document we propose to study the control/data flow separation design methodology, using Scade and Mode-Automata, and its application in the design of an automotive system. This methodology allows to facilitate the specification of different kinds of systems and to have a better readability. It also separates the study of the different parts by using the most appropriate existing tools for each of them. To do that, we study a cruise control system with GPS which makes possible the control of a car speed depending on its position given by a GPS. This system combines both control and data processing and can be specified using our methodology. The goal of this work consists in presenting the application of our methodology on a real system and studing its advantages notably for formal verification.

Dynamical systems working have been recognized as essential in the area of computer science, under the name of reactive systems by David Harel. Synchronous languages have been proposed as a paradigm to deal with reactive systems and develop tools for them. In this paper we introduce synchronous programming paradigm via the notion of multiclock dynamical systems and illustrate it via the SIGNAL language. We give an outline of controller synthesis in SIGNAL, and system/architecture design.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Ba special value, written? (pronounce “absent”) to refer to absence. Therefore, for a signal (x k k0 in the usual sense,

Hybrid systems modeling languages that mix discrete and continuous time signals and systems are widely used to develop Cyber-Physical systems where control software interacts with physical devices. Compilers play a central role, statically checking source models, generating intermediate representations for testing and verification, and producing sequential code for simulation and execution on target platforms. This paper presents a novel approach to the design and implementation of a hybrid systems language, built on synchronous language principles and their proven compilation techniques. The result is a hybrid systems modeling language in which synchronous programming constructs can be mixed with Ordinary Differential Equations (ODEs) and zero-crossing events, and a runtime that delegates their approximation to an off-the-shelf numerical solver. We propose an ideal semantics based on non standard analysis, which defines the execution of a hybrid model as an infinite sequence of infinitesimally small time steps. It is used to specify and prove correct three essential compilation steps: (1) a type system that guarantees that a continuous-time signal is never used where a discrete-time one is expected and conversely; (2) a type system that ensures the absence of combinatorial loops; (3) the generation of statically scheduled code for efficient execution. Our approach has been evaluated in two implementations: the academic language Zélus, which extends a language reminiscent of Lustre with ODEs and zero-crossing events, and the industrial prototype Scade Hybrid, a conservative extension of Scade 6.

Despite the irresistible growth of interest in formal methods and related validation and veri cation tools, the development of distributed systems seldom relies on them. We claim this is mainly due to formal methods lack of support for modern software life-cycles. The construction and maintenance of open distributed systems are mostly based on object-oriented software development. We investigate how frameworks may help to embed formal validation techniques in an object-oriented process based on the UML notation. We show how standard model-checking techniques can be used right now on UML models by exploiting informations available in class and deployment diagrams, and using an operational semantics of statecharts. We also present how the behavioural views of UML, including sequence or collaboration diagrams could be consistently managed using a common semantics model called BDL (standing for \Behavioural Description Language") with which the various behavioural views of UML can be translated into one another. BDL is a reactive synchronous language with a true concurrency semantics. Basic object interactions are represented in BDL by partially ordered sets of events and the behaviour of a complete (or incomplete) system is expressed by composition of basic interactions. BDL o ers new perspectives for a exible veri cation of systems by modeling them as globally asynchronous networks of locally synchronous software components.

Hybrid modeling tools like Simulink have evolved from simulation platforms into development platforms on which testing, verification and code generation are also performed. It is critical to ensure that the results of simulation, compilation and verification are consistent. Synchronous languages have addressed these issues but only for discrete systems. Reprising earlier work, we present a hybrid modeler built from a synchronous language and an off-the-shelf numerical solver. The main novelty is a language with hierarchical automata that can be arbitrarily mixed with data-flow and ordinary differential equations (ODEs). A type system statically ensures that discrete state changes are aligned with zero-crossing events and that the function passed to the numerical solver has no side-effects during integration. Welltyped programs are compiled by source-to-source translation into synchronous code which is then translated into sequential code using an existing synchronous language compiler.

Coal gasification is a new and clean coal conversion technology that converts coal to liquids and synthetic gas to be used in power generation and chemical products. Botswana coal was studied in a pilot plant to produce synthetic gas which can be used for power generation and chemical products (dyes, detergents, plastic, synthetic fibers, fuels). Pilot plant provides information on the amount of gas produced per mass of feed, and the amount of synthetic gas produced per variation of parameters (temperature and pressure). Every kilogram of coal produces about 95 liters of raw synthetic gas per day.

Dataflow programming languages are used in a variety of settings, and defects in their programs can have serious consequences. However, prior work in automated program repair (APR) emphasizes control flow over dataflow languages. We identify three impediments to the use of APR in dataflow programming-parallelism, state, and evaluation-and highlight opportunities for overcoming them.