• Asia pacific journal of information systems
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• v.12 no.2
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• pp.99-118
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• 2002

In this paper, we propose a visual relational database query language, VRQL, by modifying and extending the recently proposed $VOQL^*$. Like $VOQL^*$, VRQL, based on ven Diagram and graph, naturally reflects the structure of schemas in queries and has recursive formal semantics. However, VRQL has relationally complete expressiveness, while $VOQL^*$ is only a conjunctive query language. In the logical definition part of VRQL, which is the relational version of $VOQL^*$, most features of $VOQL^*$ are retained, and the semantics of queries are based on the tuple relational calculus. In the procedural definition part of VRQL, by introducing the concept of VRQL view and set operations, the expressiveness of VRQL is increased to the level equivalent to that of the relational algebra. Due to the introduction of VRQL views, existing queries or temporary queries used in the process of creating queries can be represented with views, so that complex queries may be represented more conveniently. Set operations, used with VRQL views, enable us to represent various queries, beyond the expressiveness of conjunctive query languages.

• Journal of the Korean Mathematical Society
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• v.54 no.5
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• pp.1521-1536
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• 2017

This paper introduces a representation style of variable binding using dependent types when formalizing meta-theoretic properties. The style we present is a variation of the Coquand-McKinna-Pollack's locally-named representation. The main characteristic is the use of dependent families in defining expressions such as terms and formulas. In this manner, we can handle many syntactic elements, among which wellformedness, provability, soundness, and completeness are critical, in a compact manner. Another point of our paper is to investigate the roles of free variables and constants. Our idea is that fresh constants can entirely play the role of free variables in formalizing meta-theories of first-order predicate logic. In order to show the feasibility of our idea, we formalized the soundness and completeness of LJT with respect to Kripke semantics using the proof assistant Coq, where LJT is the intuitionistic first-order predicate calculus. The proof assistant Coq supports all the functionalities we need: intentional type theory, dependent types, inductive families, and simultaneous substitution.

• The KIPS Transactions:PartD
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• v.13D no.1 s.104
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• pp.117-124
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• 2006

Hardware and software codesign framework called PeaCE(Ptolemy extension as a Codesign Environment) was developed. It allows to express both data flow and control flow which is described as fFSM which extends traditional finite state machine. While the fFSM model provides lots of syntactic constructs for describing control flow, it has a lack of their formality and then difficulties in verifying the specification. In order to define the formal semantics of the fFSM, in this paper, firstly the hierarchical structure in the model is flattened and then the step semantics is defined. As a result, some important bugs such as race condition, ambiguous transition, and circulartransition can be formally detected in the model.

• Language and Information
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• v.15 no.2
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• pp.47-65
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• 2011

A Korean adverb '거의(geoui)' modifies predicates to generate complex predicates which have meanings of 'nearly' complete or typical properties of the modified predicates in quantities, degrees, and frequencies. The modified predicates 'complete' or 'typical' properties are referred counterfactually as standards for the generated predicates' meanings of deficiencies. These counterfactual standards can be formalized by a counterfactual conditional operator of the intensional semantics in Cresswell(1990). The deficiencies in the quantities, degrees, or frequencies of the properties can be expressed formally introducing a world-independent measure of comparison. The measure can be manufactured out of relations between intensional things at indices and their equivalence classes. The world-independent measure of comparison has a semantic structure under-specified in quantity, degree, and frequency, and seems very well-suited in describing lexical meaning of '거의(geoui)'. The lexical-semantic analysis of '거의(geoui)' shows explicitly the plausibility of the indispensable existence of the comparing measure which works across real and counterfactual worlds in natural language meaning. On the other hand, we examined Kim, young-hee(1985)'s proposal of a transition of quantificational meaning for Korean degree adverbs, where he tried to explain the quantificational meaning of Korean degree adverbs in general including '거의(geoui)' with several syntactic and semantic constraints of 'contextual deletion'. But it is shown that the quantificational meanings of the degree adverbs which Kim(1985) discussed are also explained better by their under-specified meanings in quantities, frequencies and degrees with the world-independent measure of comparison applied to their paradigmatic lexical constraint rather than Kim(1985)'s transition of meaning.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.3
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• pp.141-149
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• 2008

Most functional programming languages allows programmers to write ambiguous rules, under the strategy that pattern-matching will be performed in a direction of 'from top to bottom' way. While providing programmers with convenience and intuitive understanding of defining default rules, such ambiguous rules may make the semantics of functional languages unclear. More specifically, it may fail to apply the equational reasoning, one of most significant advantage of functional programming, and may cause to obscure finding a formal way of translating functional languages into the ${\lambda}$-calculus; as a result, we only get an ad hoc translation. In this paper, we associate with separability of term rewriting systems, holding purely-declarative property, pattern-matching semantics of lazy functional languages. Separability can serve a formalism for translating lazy functional languages into the ${\lambda}$-calculus.

• Journal of KIISE:Software and Applications
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• v.31 no.5
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• pp.677-696
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• 2004

Component-based software engineering (CBSE) composes reusable components and develops applications with the components. CBSE is admitted to be a new paradigm that reduces the costs and times to develop software systems. The high quality of component designs can be assured if the consistency and correctness among the elements of a component are verified with formal specifications. Current formal languages for components include only some parts of contracts between interfaces, structural aspects and behavioral aspects of component, component-based system, component composition and variability. Therefore, it is not adequate to use current formal languages in all steps of a component design process. In this paper, we suggest a formal language to specify component designs Component-Z. Component-Z extends Object-Z, adds new notations to specify components. It can be possible to specify interfaces, the inner structure of a component, inner workflows, and workflows among interfaces with Component-Z. In addition, Component-Z provides the notations and semantics to specify variability with variation points, variants and required interfaces. The relation between interfaces and components is defined with mapping schemas. Parallel operator is used to specify component composition. It can be possible to describe deployed components with the specifications of component-based systems. Therefore, the formal specification language proposed in this paper can represent all elements to design components. In the case study, we specify an account management system in a bank so that we show that Component-Z can be used in all steps of component design.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.251-258
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• 2007

With the increase of a web service technology, a new access control mechanism has developed for XML documents. As a result, as legacy access control systems, access control systems has become an active research topic. In this paper, we propose a methodology to translate access control policies for XML documents into formal specification language CSP. To do this, first, we introduce a method to translate a hierarchical access to XML documents using XPath language into CSP process algebra. Second, we explain a method to represent a XML schema as a formal model like automata. Third, we present a method for representing the semantics of access control policies such as the scope of rules and confliction resolution into a process algebra language. Finally, a CSP specification example of an XML schema and path expressions aye shown to illustrate the validity of our approach.

• The KIPS Transactions:PartD
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• v.16D no.3
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• pp.339-352
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• 2009

There are a number of formal methods for distributed real-time systems in ubiquitous computing to analyze and verify the behavioral, temporal and the spatial properties of the systems. However most of the methods reveal structural and fundamental limitations of complexity due to mixture of spatial and behavioral representations. Further temporal specification makes the complexity more complicate. In order to overcome the limitations, this paper presents a new formal method, called Timed Calculus of Abstract Real-Time Distribution, Mobility and Interaction(t-CARDMI). t-CARDMI separates spatial representation from behavioral representation to simplify the complexity. Further temporal specification is permitted only in the behavioral representation to make the complexity less complicate. The distinctive features of the temporal properties in t-CARDMI include waiting time, execution time, deadline, timeout action, periodic action, etc. both in movement and interaction behaviors. For analysis and verification of spatial and temporal properties of the systems in specification, t-CARDMI presents Timed Action Graph (TAG), where the spatial and temporal properties are visually represented in a two-dimensional diagram with the pictorial distribution of movements and interactions. t-CARDMI can be considered to be one of the most innovative formal methods in distributed real-time systems in ubiquitous computing to specify, analyze and verify the spatial, behavioral and the temporal properties of the systems very efficiently and effectively. The paper presents the formal syntax and semantics of t-CARDMI with a tool, called SAVE, for a ubiquitous healthcare application.

• Journal of Information Processing Systems
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• v.14 no.2
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• pp.309-321
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• 2018

In the conventional computing environment, users use only a small number of software systems intensively. So it had been enough to check and guarantee the functional correctness and safety of a small number of giant systems in order to protect the user systems and their information inside the systems from outside attacks. However, checking the correctness and safety of giant systems is not enough anymore, since users are using various software systems or web services provided by unskilled developers. To prove or guarantee the safety of software system, a lot of research has been conducted in diverse areas of computer science. We will discuss the on-going approaches for guaranteeing or verifying the safety of software systems in this paper. We also discuss the future research challenge which must be solved with better solutions in the near future.

• Journal of Computing Science and Engineering
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• v.3 no.3
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• pp.143-164
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• 2009

This article surveys recent research in the area of language modeling (sometimes called statistical language modeling) approaches to information retrieval. Language modeling is a formal probabilistic retrieval framework with roots in speech recognition and natural language processing. The underlying assumption of language modeling is that human language generation is a random process; the goal is to model that process via a generative statistical model. In this article, we discuss current research in the application of language modeling to information retrieval, the role of semantics in the language modeling framework, cluster-based language models, use of language modeling for XML retrieval and future trends.