Ekawit Nantajeewarawat

XML Declarative Description: a language for the Semantic Web

Although XML and RDF (Resource Description Framework) are widely used languages for Web applications, they have insufficient mechanisms to fulfil the requirements of a Semantic Web. The authors show how XML Declarative Description expands the capabilities of XML and RDF to meet these requirements.

Automatic fall monitoring: a review

Falls and fall-related injuries are major incidents, especially for elderly people, which often mark the onset of major deterioration of health. More than one-third of home-dwelling people aged 65 or above and two-thirds of those in residential care fall once or more each year. Reliable fall detection, as well as prevention, is an important research topic for monitoring elderly living alone in residential or hospital units. The aim of this study is to review the existing fall detection systems and some of the key research challenges faced by the research community in this field. We categorize the existing platforms into two groups: wearable and ambient devices; the classification methods are divided into rule-based and machine learning techniques. The relative merit and potential drawbacks are discussed, and we also outline some of the outstanding research challenges that emerging new platforms need to address.

A data model for XML databases

In the proposed data model for XML databases, an XML element is directly represented as a ground (variable-free) XML expression—a generalization of an XML element by incorporation of variables for representation of implicit information and enhancement of its expressive power—while a collection of XML documents as a set of ground expressions, each describing an XML element in the documents. Axioms and relationships among elements in the collection as well as structural and integrity constraints are formalized as XML clauses. An XML database, consisting of: (i) a document collection (or an extensional database), (ii) a set of axioms and relationships (or an intensional database), (iii) a set of integrity constraints, is therefore modeled as an XML declarative description comprising a set of ground XML expressions and XML clauses. Its semantics is a set of ground XML expressions, which are explicitly described by the extensional database or implicitly derived from the database, based on the defined intensional database, and satisfy all the specified set of constraints. Thus, selective and complex queries, formulated as sets of XML clauses, about information satisfying specific criteria and possibly implicit in the database, become expressible and computable. The model thereby serves as an effective and well-founded XML database management framework with succinct representational and operational uniformity, reasoning capabilities as well as complex and deductive query supports.

Formalization of the Equivalent Transformation Computation Model

In the equivalent transformation (ET) computation model, a specification provides background knowledge in a problem domain and defines a set of queries of interest. A program is a set of prioritized transformation rules, and computation consists in successive reduction of queries using meaning-preserving transformation with respect to given background knowledge. We present a formalization of the ET model from the viewpoint of program synthesis, where not only computation but also program correctness and correctness relations are of central importance. The notion of program correctness defines “what it means for a program to be correct with respect to a specification,” and a correctness relation provides guidance on “how to obtain such a program.” The correctness relation of the ET model is established, based on which how the basic structure of the ET model facilitates program synthesis is discussed together with program synthesis strategies in this model.

Towards a Foundation for XML Document Databases

This paper develops a theoretical framework for modeling and managing XML documents by employment of Declarative Description (DD) theory. In the framework, the definition of an XML element is formally extended by incorporation of variables in order to represent inherent implicit information and enhance its expressive power. An XML document - a set of XML elements - is simply modeled as an XML declarative description which consists of object descriptions, representing XML elements in the document, and relationship descriptions, specifying relationships among the elements as well as integrity constraints. DTDs and complex queries can also be expressed and evaluated.

A Framework for Semantic Web Service Discovery and Planning

With the expanse of Internet, Web programmers have wide choice of Web services available to them. A need arises for automatic discovery of required Web services and construction of an appropriate sequence of invocation thereof. In this paper, we present a framework for automation of this task based on currently emerging technologies such as ontological knowledge bases, OWL, OWL-S, WSDL, description logic (DL), etc. Background knowledge ontologies are created based on which semantic meanings of Web services can be given through OWL-S. An agent employs OWL-S API to extract Web service metadata, and applies a DL inference engine, called Racer, for reasoning with the metadata with respect to given background knowledge. Reasoning tasks performed by Racer include profile matchmaking, input/output subsumption testing, and preconditions/effects analysis, which are basic mechanisms for Web services discovery and invocation planning. A prototype system has been implemented

A rule-based approach to activity recognition

This paper presents a rule-based framework for activity classification and illustrates how domain-specific expert knowledge and observation of data in its feature space can be used for rule construction. To demonstrate its practical value, the framework is applied on datasets collected during an orientation-independent activity recognition experiment. Through an implementation based on the Java Expert System Shell (JESS), two types of rules are compared: rules that are specifically constructed for each individual device orientation and those constructed without assuming any prior knowledge on device orientations. Overall accuracy improvements of 7.97% and 9.25% are observed on training and test datasets when orientation-specific rules are used.

Program generation in the equivalent transformation computation model using the squeeze method

In the equivalent transformation (ET) computation model, a specification provides background knowledge in a problem domain, a program is a set of prioritized rewriting rules, and computation consists in successive reduction of problems by rule application. As long as meaning-preserving rewriting rules, called ET rules, with respect to given background knowledge are used, correct computation results are guaranteed. In this paper, a general framework for program synthesis in the ET model is described. The framework comprises two main phases: (1) equivalent transformation of specifications, and (2) generation of a program from an obtained specification. A method for program generation in the second phase, called the squeeze method, is presented. It constructs a program by accumulation of ET rules one by one on demand, with the goal of producing a correct, efficient, and nonredundant program.

A Data Model for XML Databases

In the proposed data model for XML databases, an XML element is directly represented as a ground (variable-free) XML expression--a generalization of an XML element by incorporation of variables for representation of implicit information and enhancement of its expressive power--while a collection of XML documents as a set of ground expressions, each describing an XML element in the documents. Relationships among elements in the collection as well as integrity constraints are formalized as XML clauses. An XML database, consisting of: (i) a document collection (or an extensional database), (ii) a set of relationships (or an intensional database) and (iii) a set of integrity constraints, is therefore modeled as an XML declarative description comprising a set of ground XML expressions and XML clauses. Its semantics is a set of ground XML expressions, which are explicitly described by the extensional database or implicitly derived from the intensional database and satisfy all the specified set of constraints.

Defeasible Inheritance Through Specialization

Typed substitution provides a means of capturing inheritance in logic deduction systems. However, in the presence of method overriding and multiple inheritance, inheritance is known to be nonmonotonic, and the semantics of programs becomes a problematic issue. This article attempts to provide a general framework, based on Dungs argumentation theoretic framework, for developing a natural semantics for programs with dynamic nonmonotonic inheritance. The relationship between the presented semantics and perfect‐model (with overriding) semantics, proposed by Dobbie and Topor (1995), is investigated. It is shown that for inheritance‐stratified programs, the two semantics coincide. However, the proposed semantics also provides correct skeptical meanings for the programs that are not inheritance‐stratified.