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Formal language

About: Formal language is a research topic. Over the lifetime, 5763 publications have been published within this topic receiving 154114 citations.


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Journal Article
TL;DR: In this article, an approach for the verification of object-based graph grammars (OBGG) specifications using model checking is presented. This approach consists on the translation of OBGG specifications into PROMELA (process/protocol MEta LAnguage), which is the input language of the SPIN model checker.
Abstract: Distributed systems for open environments, like the Internet, are becoming more frequent and important. However, it is difficult to assure that such systems have the required functional properties. In this paper we use a visual formal specification language, called Object-Based Graph Grammars (OBGG), to specify asynchronous distributed systems. After discussing the main concepts of OBGG, we propose an approach for the verification of OBGG specifications using model checking. This approach consists on the translation of OBGG specifications into PROMELA (PROcess/PROtocol MEta LAnguage), which is the input language of the SPIN model checker. The approach we use for verification allows one to write properties based on the OBGG specification instead of on the generated PROMELA model.

46 citations

Journal ArticleDOI
30 Mar 1998
TL;DR: This paper develops algorithms for deciding if a property cannot distinguish between equivalent sequences, i.e., is closed under the equivalence relation, and shows that for such properties there is a wide class of equivalence relations for which determining closure is decidable, in fact is in PSPACE.
Abstract: In concurrency theory, there are several examples where the interleaved model of concurrency can distinguish between execution sequences which are not significantly different. One such example is sequences that differ from each other by stuttering, i.e., the number of times a state can adjacently repeat. Another example is executions that differ only by the ordering of independently executed events. Considering these sequences as different is semantically rather meaningless. Nevertheless, specification languages that are based on interleaving semantics, such as linear temporal logic (LTL), can distinguish between them. This situation has led to several attempts to define languages that cannot distinguish between such equivalent sequences. In this paper, we take a different approach to this problem: we develop algorithms for deciding if a property cannot distinguish between equivalent sequences, i.e., is closed under the equivalence relation. We focus on properties represented by regular languages, ω-regular languages, or prepositional LTL formulas and show that for such properties there is a wide class of equivalence relations for which determining closure is decidable, in fact is in PSPACE. Hence, checking the closure of a specification is no more difficult than checking satisfiability of a temporal formula. Among the closure properties we are able to handle, one finds trace closedness, stutter closedness and projective closedness, for all of which we are also able to prove a PSPACE lower bound. Being able to check that a property is closed under an equivalence relation has an immediate application in state-space exploration based verification. Indeed, the knowledge that the specification does not distinguish between equivalent execution sequences allows constructing a reduced state space where it is sufficient that at least one sequence per equivalence class is represented.

46 citations

Book ChapterDOI
29 Aug 2012
TL;DR: SQUALL is introduced, a controlled natural language for querying and updating RDF graphs that has a strong adequacy with RDF, an expressiveness close to SPARQL 1.1, and a CNL syntax that completely abstracts from low-level notions such as bindings and relational algebra.
Abstract: Formal languages play a central role in the Semantic Web An important aspect regarding their design is syntax as it plays a crucial role in the wide acceptance of the Semantic Web approach The main advantage of controlled natural languages (CNL) is to reconcile the high-level and natural syntax of natural languages, and the precision and lack of ambiguity of formal languages In the context of the Semantic Web and Linked Open Data, CNL could not only allow more people to contribute by abstracting from the low-level details, but also make experienced people more productive, and make the produced documents easier to share and maintain We introduce SQUALL, a controlled natural language for querying and updating RDF graphs It has a strong adequacy with RDF, an expressiveness close to SPARQL 11, and a CNL syntax that completely abstracts from low-level notions such as bindings and relational algebra We formally define the syntax and semantics of SQUALL as a Montague grammar, and its translation to SPARQL It features disjunction, negation, quantifiers, built-in predicates, aggregations with grouping, and n-ary relations through reification

46 citations

Book ChapterDOI
06 Jul 2010
TL;DR: The existence of a minimum recognizer is proved in a very general setting which applies in particular to any BA of subsets of a discrete space and an equational characterization of BA of languages closed under quotients is given, which extends the known results on regular languages to nonregular languages.
Abstract: We propose a new approach to the notion of recognition, which departs from the classical definitions by three specific features. First, it does not rely on automata. Secondly, it applies to any Boolean algebra (BA) of subsets rather than to individual subsets. Thirdly, topology is the key ingredient.We prove the existence of a minimum recognizer in a very general setting which applies in particular to any BA of subsets of a discrete space. Our main results show that this minimum recognizer is a uniform space whose completion is the dual of the original BA in Stone-Priestley duality; in the case of a BA of languages closed under quotients, this completion, called the syntactic space of the BA, is a compact monoid if and only if all the languages of the BA are regular. For regular languages, one recovers the notions of a syntactic monoid and of a free profinite monoid. For nonregular languages, the syntactic space is no longer a monoid but is still a compact space. Further, we give an equational characterization of BA of languages closed under quotients, which extends the known results on regular languages to nonregular languages. Finally, we generalize all these results from BAs to lattices, in which case the appropriate structures are partially ordered.

46 citations

Proceedings ArticleDOI
04 Nov 2001
TL;DR: In this paper, the parallel language equation A/spl square/X/spl sube/C has been studied in the context of modeling delay-insensitive processes and their environments.
Abstract: The problem of designing a component that, combined with a known part of a system, conforms to a given overall specification arises in several applications ranging from logic synthesis to the design of discrete controllers. We cast the problem as solving abstract equations over languages. Language equations can be defined with respect to several language composition operators such as synchronous composition, /spl middot/, and parallel composition, /spl square/; conformity can be checked by language containment. In this paper, we address parallel language equations. Parallel composition arises in the context of modeling delay-insensitive processes and their environments. The parallel composition operator models an exchange protocol by which an input is followed by an output after a finite exchange of internal signals. It abstracts a system with two components with a single message in transit, such that at each instance either the components exchange messages or one of them communicates with its environment, which submits the next external input to the system only after the system has produced an external output in response to the previous input. We study the most general solutions of the language equation A/spl square/X/spl sube/C, and define the language operators needed to express them. Then we specialize such equations to languages associated with important classes of automata used for modeling systems, e.g., regular languages and FSM languages. In particular, for A/spl square/X/spl sube/C, we give algorithms for computing: the largest FSM language solution, the largest complete solution, and the largest solution whose composition with A yields a complete FSM language. We solve also FSM equations under bounded parallel composition. In this paper, we give concrete algorithms for computing such solutions, and state and prove their correctness.

46 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202237
2021113
2020175
2019173
2018142