Formal language

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

Designing secure business processes with SecBPMN

Abstract: Modern information systems are increasingly large and consist of an interplay of technical components and social actors (humans and organizations). Such interplay threatens the security of the overall system and calls for verification techniques that enable determining compliance with security policies. Existing verification frameworks either have a limited expressiveness that inhibits the specification of real-world requirements or rely on formal languages that are difficult to use for most analysts. In this paper, we overcome the limitations of existing approaches by presenting the SecBPMN framework. Our proposal includes: (1) the SecBPMN-ml modeling language, a security-oriented extension of BPMN for specifying composite information systems; (2) the SecBPMN-Q query language for representing security policies; and (3) a query engine that enables checking SecBPMN-Q policies against SecBPMN-ml specifications. We evaluate our approach by studying its understandability and perceived complexity with experts, running scalability analysis of the query engine, and through an application to a large case study concerning air traffic management.

Declarative specification of visual languages

Abstract: In order to specify the relationship between pictures and their meaning, a class of declarative, constraint-based picture specification languages is introduced. These extend previous approaches to picture specification based on constraints and grammar formalisms. As the languages are defined as an abstract language scheme, it is ensured that they share a common declarative semantics and execution model. The declarative semantics allows both people and machines to easily reason about a specification independently of any underlying implementation. The operational semantics permit a picture specification to be used to both generate and recognize pictures defined by visual languages. Implementation techniques developed for constraint logic programs, which enable this to be done efficiently, are discussed. >

Rule-based composite event queries: the language XChange EQ and its semantics

Abstract: Web systems, Web services, and Web-based publish/subscribe systems communicate events as XML messages and in many cases, require composite event detection: it is not sufficient to react to single event messages, but events have to be considered in relation to other events that are received over time. This entails a need for expressive, high-level languages for querying composite events. Emphasizing language design and formal semantics, we describe the rule-based composite event query language XChangeEQ. XChangeEQ is designed to completely cover and integrate the four complementary querying dimensions: event data, event composition, temporal relationships, and event accumulation. Semantics are provided as a model theory with accompanying fixpoint theory, an approach that is established for rule languages but has not been applied to event queries so far. Because they are highly declarative, thus easy to understand and well suited for query optimization, such semantics are desirable for event queries.

Teaching Formal Languages by an Intelligent Tutoring System.

Abstract: For separating waste from a fiber-and-waste mixture in a textile machine, the mixture is tangentially thrown from a rotating roll by centrifugal force. An air flow is directed onto the traveling particles of the mixture such that fibers are returned to the roll, while the waste particles are allowed to continue their travel. Subsequently, the waste particles are removed by suction.

Signed real measure of regular languages

Abstract: This paper reviews and extends the recent work on signed real measure of regular languages for discrete-event supervisory control within a unified framework. The language measure provides total ordering of any set of partially ordered sublanguages of a regular language to allow quantitative evaluation of the controlled behavior of deterministic finite state automata under different supervisors. The paper presents a procedure by which performance of different supervisors can be evaluated based on a common quantitative tool. Two algorithms are discussed for computation of the language measure. A physical interpretation of the language measure is given from the perspective of discrete-event supervisory control synthesis.