RDFS Research Articles

A framework for medical visual information exchange on the WEB

The web has become such an extensive health information repository in the world that it is increasingly difficult to search for relevant medical information. Most medical information available on the web is not peer reviewed, and is retrieved imprecisely by current web search mechanisms (i.e. based on keywords). This paper presents the MedISeek metadata model that allows one to describe medical visual information (i.e. medical images) of different modalities, including their properties, components, relationships and authorship. The model uses the web architecture and supports the international classification of diseases and related health problems (i.e. ICD-10). An RDF schema (Resource Description Framework (RDF), http://www.w3.org/RDF/.) derived from this metadata model is integrated to each medical image, and specifies the semantics of each property in the image. Thus, relevant information can be extracted directly from the images, and data integrity is better preserved in the web. A prototype, presented here, has been built to validate the metadata model, and the mechanism for medical visual information exchange on the web. Our preliminary experimental results indicate that authorized users of our system have been able to describe, store and retrieve medical images and their associated diagnostic information.

On the Decidability and Complexity of Integrating Ontologies and Rules

We prove that entailment for RDF Schema (RDFS) is decidable, NP-complete, and in P if the target graph does not contain blank nodes. We show that the standard set of entailment rules for RDFS is incomplete and that this can be corrected by allowing blank nodes in predicate position. We define semantic extensions of RDFS that involve datatypes and a subset of the OWL vocabulary that includes the property-related vocabulary (e.g. FunctionalProperty), the comparisons (e.g. sameAs and differentFrom) and the value restrictions (e.g. allValuesFrom). These semantic extensions are in line with the if-semantics of RDFS and weaker than the iff-semantics of D-entailment and OWL (DL or Full). For these semantic extensions we present entailment rules, prove completeness results, prove that consistency is in P and that, just as for RDFS, entailment is NP-complete, and in P if the target graph does not contain blank nodes. There are no restrictions on use to obtain decidability: classes can be used as instances.

Completeness, Decidability and Complexity of Entailment for RDFSchema and a Semantic Extension Involving the OWL Vocabulary

We prove that entailment for RDFS (RDF Schema) is decidable, NP-complete, and in P if the target graph does not contain blank nodes.We show that the standard set of entailment rules for RDFS is incomplete and that this can be corrected by allowing blank nodes in predicate position. We define semantic extensions of RDFS that involve datatypes and a subset of the OWL vocabulary that includes the property-related vocabulary (e.g. Functional- Property), the comparisons (e.g. sameAs and differentFrom) and the value restrictions (e.g. allValuesFrom). These semantic extensions are in line with the 'if-semantics' of RDFS and weaker than the 'iff-semantics' of D-entailment and OWL (DL or Full). For these semantic extensions we present entailment rules, prove completeness results, prove that consistency is in P and that, just as for RDFS, entailment is NP-complete, and in P if the target graph does not contain blank nodes. There are no restrictions on use to obtain decidability: classes can be used as instances.

Introduction to RDF and RDF Schema

Introduction to RDF and RDF Schema

TRANSFORMATION FROM SEMANTIC DATA MODEL TO RDF

There have been several efforts to use relational model and database to store and manipulate Resource Description Framework (RDF). They have one general disadvantage, i.e. one is forced to map the model of semantics of RDF into relational model, which will end up in constraints and additional properties, such as, validating each assertion against the RDF schema which also stored as a triplets table. In this paper, we introduce Semantic Data Model as a proposed data model language to store and manipulate Resource Description Framework. This study also tries to prescribe the procedure on transforming a semantic data model into a RDF data model. Keyworsd: Semantic Data Model, Resource Description Framework.

RAL: An Algebra for Querying RDF

To make the World Wide Web machine-understandable there is a strong demand both for languages describing metadata and for languages querying metadata. The Resource Description Framework (RDF), a language proposed by W3C, can be used for describing metadata about (Web) resources. RDF Schema (RDFS) extends RDF by providing means for creating application specific vocabularies (ontologies). While the two above languages are widely acknowledged as a standard means for describing Web metadata, a standardized language for querying RDF metadata is still an open issue. Research groups coming both from industry and academia are presently involved in proposing several RDF query languages. Due to the lack of an RDF algebra such query languages use APIs to describe their semantics and optimization issues are mostly neglected. This paper proposes RAL (an RDF algebra) as a reference mathematical study for RDF query languages and for performing RDF query optimization. We define the data model, we present the operators to manipulate the data, and we address the application of RAL for query optimization. RAL includes: extraction operators to retrieve the needed resources from the input RDF model, loop operators to support repetition, and construction operators to build the resulting RDF model.

A development methodology for e-Work ontology using RDF/RDFS and PSL

The information sources for the e-Work environment are heterogeneous and distributed, and their contents are not machine-understandable. In this article, in order to integrate the syntax and the semantics of this information, we propose a development methodology for e-Work ontology using Resource Description Framework (RDF), RDF Schema (RDFS) and Process Specification Language (PSL). In a layered architecture, we use RDF/RDFS for the data of resources and the taxonomy of the PSL-ontology terms, and we use PSL, which is represented as eXtensible Markup Language (XML), for the process and the inference of the meaning of it. In this way, we can present an integrated representation of the data and the process in the distributed environment of e-Work. We illustrate the ontology building methodology by giving an example of e-Work scenario and application procedure, which is quoted from the RosettaNet e-Business standard and concerns order management, such as quotation and purchase order. The ontology is applied to the scenario.

On integrating rules into the Semantic Web

The Semantic Web effort of W3C aims at enhancing the web with reasoning capabilities. The approach is to design several tightly related (“layered”) languages for description of web resources and reasoning about them. This note briefly surveys the roles of the languages proposed so far: RDF, RDF Schema and the Web Ontology Language OWL, and refers to their known relations to the Description Logics. The next, not yet existing, layer of the Semantic Web, should be a rule layer. Several rule languages may be needed, depending on the applications. Horn logic is often considered a starting point for further extensions. Thus, for adding rules on top of the web ontology layer a relevant question is how to combine Horn logic with Description Logics. Some known approaches to this problem are briefly summarized.

시맨틱웹을 위한 온톨로지 언어와 구현사례 연구

지식을 축적하고 활용하기 위한 계속된 시도들이 '시맨틱 웹'이라는 개념에까지 이르게 되었는데, 시맨틱 웹이란 결국 인간의 지식을 정형화하겠다는 정보조직의 욕구에서 비롯된 산물로써, 인간이 언어로 표현하는 지식을 정형화하는 방법을 제시하고 이를 표준 웹 환경으로 통합하여 미래의 웹 환경을 일종의 통합된 목록시스템으로 구현하려는 노력이라고 볼 수 있다. 본 연구에서는 시맨틱 웹의 전반적인 개요와 시맨틱 웹을 구현하기 위한 기반인 RDF 스키마 및 여러 온톨로지 언어의 특징과 역할에 대해 살펴보고 몇가지 온톨로지를 기반으로 한 응용 연구를 소개하였다. 또한, W3C를 중심으로 시맨틱 웹을 위한 표준 온톨로지 언어로 제안된 OWL(Web Ontology Language)을 바탕으로 패싯형 시소러스인 AAT(Art and Architecture Thesaurus)의 개념 체계를 이용한 온톨로지 스키마를 구현하여 시맨틱 웹 환경의 온톨로지 기반 시스템의 구축사례로 제시하였다. Continual attempts to accumulate and apply information eventually gave birth to the concept of the "Semantic Web". Thus, the "Semantic Web" can be defined as a product of mankind's desire to standardize information. At the same time, the term provides "a method that standardizes mankind's concept of linguistical expression", and can be noted as an effort to combine such methods into a standard web environment that may materialize to form a catalogue. This study introduced RDF schema, ontology languages for the semantic web, and ontology-based systems. The purpose of the study was to construct a system based on the semantic web environment's ontology by utilizing the ontology schema derived from the facettype Art and Architecture Thesaurus(AAT). The aforementioned ontology schema is based on the Web Ontology Language(OWL), which is being widely considered the standard ontology language for the W3C-centered semantic web environment.

Using TRIPLE for business agents on the Semantic Web

This paper presents TRIPLE [Sintek and Decker, First International Semantic Web Conference, 2002], a modular rule language for the Semantic Web [Weaving the Web, The Original Design and Ultimate Destiny of the World Wide Web by Its Inventor, 1999], and its usage for business agents. TRIPLE is based on Horn logic [Foundations of Logic Programming, 1984] and borrows many basic features from F-Logic [J. ACM 42 (1995) 741] but is especially designed for querying and transforming RDF models [ http://www.w3.org/RDF/]. TRIPLE can be viewed as a successor of SiLRI (Simple Logic-based RDF Interpreter [QL’98—The Query Languages Workshop, 1998]). One of the most important differences to F-Logic and SiLRI is that TRIPLE does not have fixed semantics for object-oriented features like classes and inheritance. Its modular architecture allows such features to be easily defined for different object-oriented and other data models like UML, Topic Maps, or RDF Schema [ http://www.w3.org/TR/2000/CR-rdf-schema-20000327/]. Description logics extensions of RDF (Schema) like OIL [ http://www.ontoknowledge.org/oil/] and DAML+OIL [ http://www.daml.org/2001/03/daml+oil-index.html] that cannot be fully handled by Horn logic are provided as modules that interact with a description logic classifier, e.g. FaCT [ http://www.cs.man.ac.uk/~horrocks/FaCT/], resulting in a hybrid rule language. This paper sketches syntax and semantics of TRIPLE and shows how it can be used to declaratively specify the behavior of (business) agents.

기본의미등록기의 RDF/OWL 연계방안에 관한 연구

기본의미등록기(BSR)는 전자상거래 및 EDI 관련 시스템 사이의 상호연동을 가능하게 하기 위한 등록기이다. XML 기반 BSR 등록개체들의 구조정보나 다양한 관계의 자동추출은 현재 불가능하다. 이 연구에서는 BSR에 등록되는 정보를 자원기술-프레임웍(RDF)과 웹온톨로지언어(OWL)에 기반하는 기계가독형으로 정의한 대표적인 예를 제시하고 결론적으로 5개의 기본 권고안을 도출하였다. 즉 BSR 컴포넌트 소속의 클래스 정의에서 동의어의 표현에는 OWL의 'sameAs', 유사어 표현에는 OWL의 'equivalenlClass', BSR 개념들 간의 상.하 관계 표현은 RDF 스키마의 'subClassOF', BSR의 의미단위(BSU)에 관한 정의는 RDF 스키마의 'label', 인스턴스 용례에 관한 설명은 RDF 스키마의 'comment', 각 BSU의 클래스 소속에 관한 정의는 RDF 스키마의 'domain', BSU가 취할 수 있는 데이터유형에 대한 정의는 RDF 스키마의 'range'등을 적용하며, 나아가 BSR 데이터요소의 정의에 XML 스키마의 데이터 유형을 접목시키고 BSU들 간의 상.하 관계 표현에 RDF 스키마의 'subPropertyOF'를 적용할 것을 추천하였다.

Where Are the Rules

Rules for the Semantic WebIt Rules!Semantic RulesThe Semantic Web Needs a Logic for Rules and ObjectsRules and RuleML in the Semantic WebSeven Golden Rules for a Web Rule LanguageWeb Ontology Language is now the W3C's candidate recommendation, so the promises of the Semantic Web should come closer to being realities. However, OWL cannot account for some rules. Beyond a solid foundation of RDF, RDFS, and OWL, rule standardization is missing. This issue's essays explore different approaches to solving this problem.

Design issues and challenges for RDF- and schema-based peer-to-peer systems

Databases have employed a schema-based approach to store and retrieve structured data for decades. For peer-to-peer (P2P) networks, similar approaches are just beginning to emerge. While quite a few database techniques can be re-used in this new context, a P2P data management infrastructure poses additional challenges which have to be solved before schema-based P2P networks become as common as schema-based databases. We will describe some of these challenges and discuss approaches to solve them. Our discussion will be based on the design decisions we have employed in our Edutella infrastructure, a schema-based P2P network based on RDF and RDF schemas, and will also point out additional work addressing the issues discussed.

Querying the Semantic Web with RQL

Real-scale Semantic Web applications, such as Knowledge Portals and E-Marketplaces, require the management of voluminous repositories of resource metadata. The Resource Description Framework (RDF) enables the creation and exchange of metadata as any other Web data. Although large volumes of RDF descriptions are already appearing, sufficiently expressive declarative query languages for RDF are still missing. We propose RQL, a new query language adapting the functionality of semistructured or XML query languages to the peculiarities of RDF but also extending this functionality in order to uniformly query both RDF descriptions and schemas. RQL is a typed language, following a functional approach a la OQL and relies on a formal graph model that permits the interpretation of superimposed resource descriptions created using one or more RDF schemas. We illustrate the syntax, semantics and type system of RQL and report on the performance of RSSDB, our persistent RDF Store, for storing and querying voluminous RDF metadata.

Enabling knowledge representation on the Web by extending RDF Schema

Recently, a widespread interest has emerged in using ontologies on the Web. Resource Description Framework Schema (RDFS) is a basic tool that enables users to define vocabulary, structure and constraints for expressing meta data about Web resources. However, it includes no provisions for formal semantics, and its expressivity is not sufficient for full-fledged ontological modeling and reasoning. In this paper, we will show how RDFS can be extended to include a more expressive knowledge representation language. That, in turn, would enrich it with the required additional expressivity and the semantics of that language. We do this by describing the ontology language Ontology Inference Layer (OIL) as an extension of RDFS. An important advantage to our approach is that it ensures maximal sharing of meta data on the Web: even partial interpretation of an OIL ontology by less semantically aware processors will yield a correct partial interpretation of the meta data.

Agent-based product-support logistics system using XML and RDF

The capability of the timely provision of maintenance services and service parts is critical to the competitiveness of industrial systems. To enhance the timely operations in a product-support logistics chain, business partners (equipment manufacturers, parts distributors, customers) may have to collaborate for the efficient exchange of relevant information. We propose the architecture of an agent-based product-support logistics system. Emphasis is placed on the problems of sharing and exchanging information through agent communication. We adopt the Resource Description Framework (RDF) schema for information modelling in product-support logistics domain. The eXtensible Markup Language (XML) serialization generates messages for agent communication. The use of XML and RDF enables software agents to understand the contents of messages correctly and consistently. We demonstrate the feasibility of our agent architecture using a scenario in logistical support processes. We believe that the approach can provide a promising way to the automation of business processes in product-support logistics through seamless communication among the partners.

The Syntactic Web: Syntax and Semantics on the Web

XQuery is a query language designed to allow queries across the many kinds of information that are represented in XML. Although topic maps and RDF can also be represented in XML, many have held that their many possible syntactic forms make them extremely difficult to query using an XML query language, and that they can only be queried using special-purpose query languages with built-in knowledge of their semantics, including the ability to exploit RDF schema information. This talk shows that XQuery can, in fact, be used to solve the kinds of queries for which RDF and topic map query languages were designed, though with a loss of type safety.The approach taken is to transform instances of RDF and topic maps to a syntactic representation that closely models their underlying logical models, and to use function libraries written in XQuery to directly support operations specific to RDF or topic maps. Schema-level information is also incorporated in this representation and is supported in the library, so queries can exploit type hierarchies and perform joins across predicates.Information from other XML sources can also be queried together with information from topic maps and RDF. For instance, a query on a topic map that searches for Shakespeare plays mentioned in Italian operas can also query the plays themselves - represented in XML - to determine which italian cities are mentioned in them.

ENGLISH

This article focuses on the search performance of the existing search engines on internet. Discusses few solutions for the current searching problems, and suggests the resource description framework (RDF) for organised searching. The paper includes the usefulness of RDF schema and covers the futuristic vision of RDF. http://dx.doi.org/10.14429/dbit.21.4.3545

Resource Description Framework (RDF) for Organised Searching on Internet

This article focuses on the search performance of the existing search engines on internet. Discusses few solutions for the current searching problems, and suggests the resource description framework (RDF) for organised searching. The paper includes the usefulness of RDF schema and covers the futuristic vision of RDF. http://dx.doi.org/10.14429/dbit.21.4.3545

XML, RDF, and relatives

Languages for representing data and knowledge are an important aspect of the Semantic Web, and there are a lot of languages around! Most languages are based on XML (eXtensible Markup Language) or use XML as syntax; some have connections to RDF (Resource Description Framework) or RDF schemas. This tutorial briefly introduces XML, XML schemas, RDF and RDF schemas.