CUDL language semantics: Updating FDB data

The semantics for data manipulation of the database language CUDL - Conceptual Universal Database Language - designed to manage dynamic database environments, are presented. This language conforms to the FDB (Frame DataBase) data model, offering a simple, easy and efficient platform for the use of the FDB model. Otherwise the management and operation of FDB data is laborious and time-consuming and it requires from the user a very good acquaintance of the proposed model, the structures and organisation of it as well as the processes of the management of elements that compose it. In this paper we present in depth the semantics of the way of handling the data, in order to search and transform information, in an FDB data source. We present the analysis of simple and complex cases that led us to synthesize valid and simple semantic rules that determine the data manipulation operations. The more sophisticated and demanding constructs, used in the language, for query specification, query processing and object manipulation are discussed and evaluated.     

A linguistic ontology of space for natural language processing

We present a detailed semantics for linguistic spatial expressions supportive of computational processing that draws substantially on the principles and tools of ontological engineering and formal ontology. We cover language concerned with space, actions in space and spatial relationships and develop an ontological organization that relates such expressions to general classes of fixed semantic import. The result is given as an extension of a linguistic ontology, the Generalized Upper Model, an organization which has been used for over a decade in natural language processing applications. We describe the general nature and features of this ontology and show how we have extended it for working particularly with space. Treaitng the semantics of natural language expressions concerning space in this way offers a substantial simplification of the general problem of relating natural spatial language to its contextualized interpretation. Example specifications based on natural language examples are presented, as well as an evaluation of the ontology's coverage, consistency, predictive power, and applicability.     

Enhancing ebXML Registries to Make them OWL Aware

ebXML is a standard from OASIS and UN/CEFACT which specifies an infrastructure to facilitate electronic business. In this paper, we address how ebXML registry semantics support can be further enhanced to make it OWL aware. OWL constructs are represented through ebXML registry information model constructs, and stored procedures are defined in the ebXML registry for processing the OWL semantics. These predefined stored queries provide the necessary means to exploit the enhanced semantics stored in the registry. In this way, an application program does not have to be aware of the details of how this semantics support is achieved in ebXML registry, and does not have to contain additional code to process this semantics.We believe that this approach is quite powerful to associate semantics with registry objects: it becomes possible to retrieve knowledge through queries, the enhancements to the registry are generic and also the registry specification is kept intact. The capabilities provided move the semantics support beyond what is currently available in ebXML registries and it does so by using a standard ontology language.To be able to demonstrate the benefits of the enhancements, we also show how the resulting semantics can be made use of in Web service discovery and composition.Recommended by: Athman Bouguettaya and Boualem BenatallahThis work is supported in part by the European Commission, Project No: IST-1-002104-STP SATINE and the Scientific and Technical Research Council of Turkey (TÜBÍTAK), Project No: EEEAG 104E013 and is realized as a proposal to OASIS ebXML Semantic Content Management subcommittee which is working on possible semantic extensions to the registry.     

基于Object-Z的XPath形式化语义

本文描述了XPath语言的形式化语义。一个统一的面向对象的语义视角用于建模所有XPath语言构造。语义的表示采用形式化规范语言Object-Z的符号系统。这种高度结构化的语义模型具有简洁、可组合性和可复用性的特点。     

Constructing language processors with algebra combinators

Modular Monadic Semantics (MMS) is a well-known mechanism for structuring modular denotational semantic definitions for programming languages. The principal attraction of MMS is that families of language constructs can be independently specified and later combined in a mix-and-match fashion to create a complete language semantics. This has proved useful for constructing formal, yet executable, semantics when prototyping languages. In this work we demonstrate that MMS has an additional software engineering benefit. In addition to composing semantics for various language constructs, we can use MMS to compose various differing semantics for the same language constructs. This capability allows us to compose and reuse orthogonal language tasks such as type checking and compilation. We describe algebra combinators, the principal vehicle for achieving this reuse, along with a series of applications of the technique for common language processing tasks.     

Translating Java for Multiple Model Checkers: The Bandera Back-End

One approach to model checking program source code is to view a model checker as a target machine. In this setting, program source code is translated to a model checker’s input language using a process that shares much in common with program compilation. For example, well-defined intermediate program representations are used to stage the translation through a series of analyses and optimizing transformations and target-specific details are isolated in code generation modules.In this paper, we present the Bandera Intermediate Representation (BIR)—a guarded-assignment transformation system language that has been designed to support the translation of Java programs to a variety of model checkers. BIR includes constructs, such as inheritance, dynamic creation of data, and locking primitives, that are designed to model the semantics of Java primitives. BIR also includes several non-deterministic choice constructs that support abstraction in modeling and specification of properties of dynamic heap structures.We have developed a BIR-based tool infrastructure that has been applied to develop customized analysis frameworks for several different input languages using different model checking tools. We present BIR’s type system and operational semantics in sufficient detail to support similar applications by other researchers. This semantics details several state space reductions and state space search variations. We describe the translation of Java to BIR and how BIR is translated to the input languages of several model checkers.     

Emerging OCL tools

The Object Constraint Language (OCL) is a notational language for analysis and design of software systems, which is used in conjunction with the Unified Modelling Language (UML) to specify the semantics of the building blocks precisely. OCL can also be used by other languages, notations, methods and software tools in order to specify restrictions and other expressions of their models. Likewise, OCL is used by the Object Management Group (OMG) in the definition of other fast spreading industrial standards such as Meta Object Facility (MOF) or XML Metadata Interchange (XMI).Support tools aimed at making this language easier to use are becoming available. These tools are capable of supporting and handling OCL expressions. This paper presents a comparative study of the main tools currently available, both commercial and freely available ones. The study is very practical, with the advantages and disadvantages of the different tools being pointed out. The evaluations made may be of use in helping those developers and analysts who already use the language, as well as those who intend to use it in the near future, to choose the OCL tool which best adapts to their requirements.     

UML类图的形式化及分析

统一建模语言(UML)是一种通用的图形化建模语言,在面向对象系统的分析和设计中,它已成为事实上的工业标准。但是UML不是形式化的建模语言,缺乏精确的语义描述,因此会导致一些问题。Z是一种广泛使用的形式化规约语言,Z适合用来精确地表示模型的语法和语义。文章采用Z符号来表示UML类图的组成元素的语法和语义及其映射关系,最后对UML类图的一些性质进行分析和验证。     

An agile approach to language modelling and development

We have developed novel techniques for component-based specification of programming languages. In our approach, the semantics of each fundamental programming construct is specified independently, using an inherently modular framework such that no reformulation is needed when constructs are combined. A language specification consists of an unrestricted context-free grammar for the syntax of programs, together with an analysis of each language construct in terms of fundamental constructs. An open-ended collection of fundamental constructs is currently being developed. When supported by appropriate tools, our techniques allow a more agile approach to the design, modelling, and implementation of programming and domain-specific languages. In particular, our approach encourages language designers to proceed incrementally, using prototype implementations generated from specifications to test tentative designs. The components of our specifications are independent and highly reusable, so initial language specifications can be rapidly produced, and can easily evolve in response to changing design decisions. In this paper, we outline our approach, and relate it to the practices and principles of agile modelling.     

Modelling agent communication in a first order logic

In the design of information systems, the notion of agent has proven useful. When modelling communication among agents, deontic concepts, such as obligations, permissions, and prohibitions are essential. The dynamics of obligations, i.e. how obligations are created and destroyed, can effectively be described by means of notions from speech act theory. In this paper, we present a language that includes deontic and illocutionary constructs for the modelling of communication between agents. The language is a logic programming language, which gives it a simple semantics and makes it executable. A distinguishing feature of the language is that it is able to represent time explicitly, which is required to give an adequate semantics for deontic constructs.     

Operational Semantics for MSC'96

Recently, the ITU-standardised specification language Message Sequence Chart has been extended with constructs for more complete and structured specifications. The new version of the language is called MSC'96. Currently, research is performed on the extension of the formal semantics towards a semantics for MSC'96. In this article, we aim at explaining the basic ideas behind the formal semantics. We give formal definitions of parts of the language, but most features are explained by informal examples and drawings. It takes several steps in order to follow the path from an MSC drawing to its formal meaning. First, the drawing must be converted to a concrete textual representation. This conversion is already defined implicitly in Z.120. Next, this syntax is transformed into a formal expression over some process algebra signature. MSC constructs are replaced by appropriate process algebra operators. This transformation is compositional. The operational behaviour of the process algebraic expression can be studied, or the expression can be interpreted into some mathematical model and compared to the interpretation of some other MSC.     

Circular expressions: elimination of static environments

Consider the connection between denotational semantics for a language with goto statements and flow diagrams for programs in such a language. The main point of interest is that the denotational semantics uses a recursively defined environment to give the meaning of labels, while a flow diagram merely has a jump to the appropriate program point. A simple reduction called “indirection elimination” strips away the environment from the denotational semantics and extracts an expression with cycles that is very close to the flow diagram of a program. The same idea applies to associating bodies with recursive procedures, or to any construct whose semantics is not wedded to the syntax. In addition to being a useful data structure and conceptual device, expressions with cycles are well defined mathematical objects—their semantics can be given by unfolding them into infinite structures that have been well studied. The practicality of the elimination of environments has been tested by constructing a trial implementation, which serves as the front end of a semantics directed compiler generator. The implementation takes a denotational semantics of a language and constructs a “black box” that maps programs in the language into an intermediate representation. The intermediate representation is a circular expression.     

An embeddable virtual machine for state space generation

The semantics of modelling languages are not always specified in a precise and formal way, and their rather complex underlying models make it a non-trivial exercise to reuse them in newly developed tools. We report on experiments with a virtual machine-based approach for state space generation. The virtual machine’s (VM) byte-code language is straightforwardly implementable, facilitates reuse and makes it an adequate target for translation of higher-level languages like the SPIN model checker’s Promela, or even C. As added value, it provides efficiently executable operational semantics for modelling languages. Several tools have been built around the VM implementation we developed, to evaluate the benefits of the proposed approach.     

基于自然语言处理的中文科技论文特征提取研究

随着中国科技、经济的迅速发展,中文科技论文大量以电子文本的形式存在.因此,中文科技论文文本分类研究已经成为信息处理领域中的一个热门话题.本文建立了基于自然语言处理的文本特征提取模型,并从语法、语义和语用三个层面进行了详细地分析.     

A weakest precondition semantics for refinement of object-orientedprograms

We define a predicate-transformer semantics for an object oriented language that includes specification constructs from refinement calculi. The language includes recursive classes, visibility control, dynamic binding, and recursive methods. Using the semantics, we formulate notions of refinement. Such results are a first step toward a refinement calculus     

Interactive Analysis of Word Vector Embeddings

Word vector embeddings are an emerging tool for natural language processing. They have proven beneficial for a wide variety of language processing tasks. Their utility stems from the ability to encode word relationships within the vector space. Applications range from components in natural language processing systems to tools for linguistic analysis in the study of language and literature. In many of these applications, interpreting embeddings and understanding the encoded grammatical and semantic relations between words is useful, but challenging. Visualization can aid in such interpretation of embeddings. In this paper, we examine the role for visualization in working with word vector embeddings. We provide a literature survey to catalogue the range of tasks where the embeddings are employed across a broad range of applications. Based on this survey, we identify key tasks and their characteristics. Then, we present visual interactive designs that address many of these tasks. The designs integrate into an exploration and analysis environment for embeddings. Finally, we provide example use cases for them and discuss domain user feedback.