Pattern-driven Programming in Scala

This is an experimental exploration of the pattern-driven programming paradigm—the sole use of pattern matching to determine the next instruction or execute. We define a pure pattern-driven programming language named PA-Scala by defining a subset of the Scala programming language, which restricts sequence control to the powerful pattern matching facilities in Scala. We use PA-Scala to explore the strengths and limitations of pattern-driven programming. By implementing a phrase structure grammar solver in PA-Scala, we show that pattern-driven programming can be used to solve general computation problems. We then implement a Prolog interpreter in PA-Scala, which demonstrates how resolution and unification can be implemented in PA-Scala. Finally we analyzed the possibility of parallel execution for PA-Scala, and show that pattern-driven programming also has the potential to achieve performance improvements by running pattern matching operations in parallel

Representing Conversations for Scalable Overhearing

Open distributed multi-agent systems are gaining interest in the academic community and in industry. In such open settings, agents are often coordinated using standardized agent conversation protocols. The representation of such protocols (for analysis, validation, monitoring, etc) is an important aspect of multi-agent applications. Recently, Petri nets have been shown to be an interesting approach to such representation, and radically different approaches using Petri nets have been proposed. However, their relative strengths and weaknesses have not been examined. Moreover, their scalability and suitability for different tasks have not been addressed. This paper addresses both these challenges. First, we analyze existing Petri net representations in terms of their scalability and appropriateness for overhearing, an important task in monitoring open multi-agent systems. Then, building on the insights gained, we introduce a novel representation using Colored Petri nets that explicitly represent legal joint conversation states and messages. This representation approach offers significant improvements in scalability and is particularly suitable for overhearing. Furthermore, we show that this new representation offers a comprehensive coverage of all conversation features of FIPA conversation standards. We also present a procedure for transforming AUML conversation protocol diagrams (a standard human-readable representation), to our Colored Petri net representation

Reachability and error diagnosis in LR(1) automata

National audienceGiven an LR(1) automaton, what are the states in which an error can be detected? For each such " error state " , what is a minimal input sentence that causes an error in this state? We propose an algorithm that answers these questions. Such an algorithm allows building a collection of pairs of an erroneous input sentence and a diagnostic message, ensuring that this collection covers every error state, and maintaining this property as the grammar evolves. We report on an application of this technique to the CompCert ISO C99 parser, and discuss its strengths and limitations

Coverage directed algorithms for test suite construction from LR-automata

Thesis (MSc)--Stellenbosch University, 2022.ENGLISH ABSTRACT: Bugs in software can have disastrous results in terms of both economic cost and human lives. Parsers can have bugs, like any other type of software, and must therefore be thoroughly tested in order to ensure that a parser recognizes its intended language accurately. However, parsers often need to recognize many different variations and combinations of grammar structures which can make it time consuming and difficult to construct test suites by hand. We therefore require automated methods of test suite construction for these systems. Currently, the majority of test suite construction algorithms focus on the grammar describing the language to be recognized by the parser. In this thesis we take a different approach. We consider the LR-automaton that recognizes the target language and use the context information encoded in the automaton. Specifically, we define a new class of algorithm and coverage criteria over a variant of the LR-automaton that we define, called an LR-graph. We define methods of constructing positive test suites, using paths over this LR-graph, as well as mutations on valid paths to construct negative test suites. We evaluate the performance of our new algorithms against other state-of-the-art algorithms. We do this by comparing coverage achieved over various systems, some smaller systems used in a university level compilers course and other larger, real-world systems. We find good performance of our algorithms over these systems, when compared to algorithms that produce test suites of equivalent size. Our evaluation has uncovered a problem in grammar-based testing algorithms that we call bias. Bias can lead to significant variation in coverage achieved over a system, which can in turn lead to a flawed comparison of two algorithms or unrealized performance when a test suite is used in practice. We therefore define bias and measure it for all grammar-based test suite construction algorithms we use in this thesis.AFRIKAANSE OPSOMMING: Foute in sagteware kan rampspoedige resultate hˆe in terme van beide eko nomiese koste en menselewens. Ontleders kan foute hˆe soos enige ander tipe sagteware en moet daarom deeglik getoets word om te verseker dat ’n ontleder sy beoogde taal akkuraat herken. Ontleders moet egter dikwels baie verskillende variasies en kombinasies van grammatikastrukture herken wat dit tydrowend en moeilik kan maak om toetsreekse met die hand te bou. Ons benodig dus outomatiese metodes van toetsreeks-konstruksie vir hierdie stelsels. Tans fokus die meeste toetsreeks-konstruksiealgoritmes op die grammatika wat die taal beskryf wat deur die ontleder herken moet word. In hierdie tesis volg ons ’n ander benadering. Ons beskou die LR-outomaat wat die teikentaal herken en gebruik die konteksinligting wat in die outomaat ge¨enkodeer is. Spesifiek, ons definieer ’n nuwe klas algoritme en dekkingskriteria oor ’n variant van die LR-outomaat wat ons definieer, wat ’n LR-grafiek genoem word. Ons definieer metodes om positiewe toetsreekse te konstrueer deur paaie oor hierdie LR-grafiek te gebruik, asook mutasies op geldige paaie om negatiewe toetsreekse te konstrueer. Ons evalueer die werkverrigting van ons nuwe algoritmes teenoor ander moderne algoritmes. Ons doen dit deur dekking wat oor verskeie stelsels behaal is, te vergelyk, sommige kleiner stelsels wat in ’n samestellerskursus op universiteitsvlak en ander groter werklike stelsels gebruik word. Ons vind goeie werkverrigting van ons algoritmes oor hierdie stelsels, in vergelyking met algoritmes wat toetsreekse van ekwivalente grootte produseer. Ons evaluering het ’n probleem in grammatika-gebaseerde toetsalgoritmes ontdek wat ons vooroordeel noem. Vooroordeel kan lei tot aansienlike variasie in dekking wat oor ’n stelsel behaal word, wat weer kan lei tot ’n gebrekkige vergelyking van twee algoritmes of ongerealiseerde prestasie wanneer ’n toets reeks in die praktyk gebruik word. Ons definieer dus vooroordeel en meet dit vir alle grammatika-gebaseerde toetsreeks-konstruksiealgoritmes wat ons in hierdie tesis gebruik.Master

An Entailment Checker for Separation Logic with Inductive Definitions An Entailment Checker for Separation Logic with Inductive Definitions

International audienceIn this paper, we present Inductor, a checker for entailments between mutually recursive predicates, whose inductive definitions contain ground constraints belonging to the quantifier-free fragment of Separation Logic. Our tool implements a proof-search method for a cyclic proof system that we have shown to be sound and complete, under certain semantic restrictions involving the set of constraints in a given inductive system. Dedicated decision procedures from the DPLL(T)-based SMT solver CVC4 are used to establish the satisfiability of Separation Logic formu-lae. Given inductive predicate definitions, an entailment query, and a proof-search strategy, Inductor uses a compact tree structure to explore all derivations enabled by the strategy. A successful result is accompanied by a proof, while an unsuccessful one is supported by a counterexample

26. Theorietag Automaten und Formale Sprachen 23. Jahrestagung Logik in der Informatik: Tagungsband

Der Theorietag ist die Jahrestagung der Fachgruppe Automaten und Formale Sprachen der Gesellschaft für Informatik und fand erstmals 1991 in Magdeburg statt. Seit dem Jahr 1996 wird der Theorietag von einem eintägigen Workshop mit eingeladenen Vorträgen begleitet. Die Jahrestagung der Fachgruppe Logik in der Informatik der Gesellschaft für Informatik fand erstmals 1993 in Leipzig statt. Im Laufe beider Jahrestagungen finden auch die jährliche Fachgruppensitzungen statt. In diesem Jahr wird der Theorietag der Fachgruppe Automaten und Formale Sprachen erstmalig zusammen mit der Jahrestagung der Fachgruppe Logik in der Informatik abgehalten. Organisiert wurde die gemeinsame Veranstaltung von der Arbeitsgruppe Zuverlässige Systeme des Instituts für Informatik an der Christian-Albrechts-Universität Kiel vom 4. bis 7. Oktober im Tagungshotel Tannenfelde bei Neumünster. Während des Tre↵ens wird ein Workshop für alle Interessierten statt finden. In Tannenfelde werden • Christoph Löding (Aachen) • Tomás Masopust (Dresden) • Henning Schnoor (Kiel) • Nicole Schweikardt (Berlin) • Georg Zetzsche (Paris) eingeladene Vorträge zu ihrer aktuellen Arbeit halten. Darüber hinaus werden 26 Vorträge von Teilnehmern und Teilnehmerinnen gehalten, 17 auf dem Theorietag Automaten und formale Sprachen und neun auf der Jahrestagung Logik in der Informatik. Der vorliegende Band enthält Kurzfassungen aller Beiträge. Wir danken der Gesellschaft für Informatik, der Christian-Albrechts-Universität zu Kiel und dem Tagungshotel Tannenfelde für die Unterstützung dieses Theorietags. Ein besonderer Dank geht an das Organisationsteam: Maike Bradler, Philipp Sieweck, Joel Day. Kiel, Oktober 2016 Florin Manea, Dirk Nowotka und Thomas Wilk