Documents stored in a database system can have complex internal structure described by languages such as SGML. How to take advantage of this structure presents challenges for database system implementors. We classify the types of queries that need to be supported by SGML-conformant database systems. We then describe several data models that have been proposed for representing documents in a database system and discuss the support these models provide for SGML. Finally we consider query evaluation.

In order to make the hyperling generation mechanism not only dynamic but also systematic, we will mainly describe the use of the querying and abstraction facilities in hypertext database systems. Our work focuses on a dynamic, abstract and systematic link generation mechanism. The prototype system named TextLink/Gem is implemented by taking an object-oriented approach, and the notions of anchor objects, query-pair links, polymorphic links and inheritable links, on which the system is based, and their implementations are described in detail.

This paper describes the architecture and storage structure of a new interactive multimedia information system called VideoReality. VideoReality is based on a visual conducting model, which describes the information retrieval process that occurs when people observe visible objects in the real world. VideoReality provides a spatial and temporal spread of a virtual video space from a set of stored video streams. The video space has a three-layered structure similar to that of the ANSI/X3/SPARC three-schema architecture. Users can move their eyes and watch objects freely in the video space, just as if they were viewing the real world. This paper also presents a prototype application system called Electronic Aquarium'

This papaer presents a data model and the database system architecture to handle multimedia data, especially video (or image sequence) data. A new scheme AIS diagram" is introduced, by which all informations about entities and relationships among bitmap frames or textual informations are described in a uniform way. We focus on the integration of engineering data. The most important problem to be solved is how to capture the objects" in each frame and to represent them in the data model. For this purpose we propose physical cut" and logical cut" as a unit of information in image sequences and, using those concepts, we developed a prototype system for multimedia data processing on a conventional database system.

Queries to generate a map from geographic detabases are too large and complex for users to specify all components in it. Thematic parts of the map should be described by users as ad hoc queries. However, background parts of it should be inferred from users' queries corresponding to the thematic parts. Furthermore, it is important for the map systems to lead users' constructing their ad hoc queries and to infer visualization methods applied to the data retrieved by the ad hoc queries. This paper discusses a framework to infer supplemental queries and visualization methods in order to make the retrieval results into a feasible map using geographic domain hierarchical levels, geographic domain thesauruses and existing example queries. The framework allows users to know mismatches of components in queries, inappropriate queries for maps, and deriving candidates for additional components in queries.

Scientific database systems for the analysis of genes and proteins are becoming very important these days. We have developed a deductive database system PACADE for analyzing the three dimensional and secondary structures of proteins. In this paper, we describe the statistical data classification component of PACADE. We implemented the component for cluster analysis and discrimination analysis. In addition, we enhanced the aggregation function in order to calculate the characteristic values which are useful for data classification. By using the cluster analysis function, the proteins are thereby classified into different types of structural characteristics. The results of these structural analysis experiments are also described in this paper.

The evolution of heterogeneous and autonomous databases research has been slow compared to other areas of research. Part of the problem resides in the fact that bridging data semantics has been a difficult problem. Sharing data among disparate databases has mostly been achieved through some form of manual schema integration. The complexity of making autonomous heterogeneous databases smoothly interoperate is dependent on addressing two major issues. The first issue to address is what adequate levels of autonomy databases are guaranteed to keep. The second issue to address is what overhead cost is required to bridge database heterogeneity. The complexity of these two issues are closely dependent on how scalable multidatabase systems are. In this paper we introduce the FINDIT architecture which uses information meta-types to provide a basis for such an organization and, consequently, provides a platform for inter-operability. A distinction is made between the information and inter-node relationship spaces to achieve scalability. Tassili language primitives are used for the incremental building of dynamic inter-node relationships based upon usage considerations.

Our objective is to resolve three types of heterogeneity - data model,database system, and semantic - in heterogeneous databases. The basic framework which we propose for this objective is realized in an autonomous decentralized database system (i.e., an interoperable database system), called Jasmine/M. Users describe their relational or object-oriented data models and schemas locally using the model primitives which Jasmine/M provides as a scripting language. Description using such primitives or scripts constitutes viewports, which have a role to resolve heterogeneity in data models and database systems at local sites. At relational viewports, both relational and object-oriented schemas defined at other sites are translated via scripts and are viewed as relational schemas. Similarly at object-oriented viewports, any schema defined at other sites is viewed object-oriented schemas. Relational and object-oriented views are used to resolve semantic heterogeneity within viewports. This paper describes a step wise approach to resolving the three types of heterogeneity, using scripts, viewports, and views, and its implementation using active objects.

As the Hypertext Transfer Protocol (HTTP) becomes more popular for network communication, network loads in areas with less developed network infrastructures will be an increasing problem. This paper presents a system which extends a WWW-server with a gateway to an RDBMS and a mail program, allowing for interactive query formulation together with return of potentially large query results by e-mail. These results can then be downloaded by the user when network loads are low.

Flora is a functional-style language for object and relational algebra. It has been designed for efficient support of advanced database languages combining rules and objects using compilation and optimization. Flora is a strongly typed language based on an OO data model and incorporating support for collection-oriented computational capabilities. In this paper, we describe the design and architecture of the Flora optimizer which is rule-based, yet doing cost-based optimization. The optimizer uniformly captures logical, semantic and implementation knowledge regarding the execution system and the applications by means of assertions. This framework eases extensibility and enables efficient query rewriting.

Efficient retrieval of nested objects is an important issue in advanced database systems. So far, a number of indexing methods for nested objects have been proposed. However, they do not consider retrieval of nested objects based on the set comparison operators such as and . Previouly, we proposed four set access facilities for nested objects and compared their performance in terms of retrieval cost, storage cost, and update cost. In this paper, we extend the study and present refined algorithms and cost formulas applicable to more generalized situations. Our cost models and analysis not only contribute to the study of set-valued retrieval but also to cost estimation of various indexing methods for nested objects in general.

Generalizations of the classical ngram indexing techique provide a powerful tool for the fast retrieval of tree structures. We investigate the special case of binary trees, which are heavily used, for example, in computer linguistics: Given a database T{t₁,...,t_n} of labeled binary trees and a query tree q, find efficiently all trees t T that contain q as subtree. For supporting queries of this type, we propose an indexing technique that covers the database trees t T with smaller trees of a fixed calss. Thus, each index record represents a subtree that is contained in at least one database tree. To answer a given query q, the database trees of T that contain all of q's cover trees are preselected as candidates, which in turn are tested rigorously for containment of q. We present results from two test suites: one with databases of 10,000 randomly generated binary trees each and one with the 29,394 most extensive phrase structure trees found in the morphosyntactical analysis of the Old Testament's Hebrew texts Genesis, Exodus,and Leviticus.

In this paper, we describe a distributed paged-object server to efficiently support the storage management for new generation database management systems. This storage server is based on distributed client/server architecture, and allows clients to directly map database files onto distributed shared virtual memory (DSVM). In this architecture, there is a server at each site and the server only supports the clients in the same site. This improves performance utilizing client machine resources and offloading the shared resourcer server machine and the network. Therefore, this architecture may avoid drawbacks such as bottleneck in a traditional centralized client/server architecture, and also may reduces network traffic and improve performance efficiency of remote file access using Net File System (NFS). Moreover, this architecture allows distributed shared objects to reside and execute anywhere and to be used by any clients on the network. A prototype system (called WAKASHI/D) is implemented under the Mach operating system. The distributed, shared, and transactional virtual memory that the system supports is either volatile or persistent and they can be accessed by user applications in a uniform way. This paper also presents a performance evaluation and analysis of WAKASHI/D to compare its centralized version WAKASHI/C and demonstrates that the distributed server has substantial performance benefits.

As Object-Oriented Database Systems (OODBS) play an increasingly important role in advanced database systems, OODBS performance becomes a significant issue. It is well known that there is a strong relationship between performance and the concurrency control algorithms employed by the Database Management System (DBMS). Class Granularity Locking (CGL) and Class Hierarchy Granularity Locking (CHGL) are proposed as the concurrency control algorithms for OODBS to minimize the locking overhead. However, their basic characteristics, including the licking overhead and concurrency, have not been extensively investigated and it is not known which one is most appropriate for the general case. In this paper, we construct a simulation model for OODBS and carry out several performance evaluation studies on these two Class-Hierarchy Locking protocols and the Non Class-Hierarchy Locking (NCL) protocol. The NCL protocal is a variation of the conventional two phase locking protocol being applied to OODBS data structures.

For a complex object model, a form of range restriction, called specialization constraint (SC), has been studied. On the other hand, very few models have been proposed that support selective inheritance. In this paper, the following consideration is taken into SCs for a complex object medel suppoorting selective inheritance. A polynomial-time algorithm is given for deciding if a given database schema is well-formed. A sound and complete axiomatization for SCs is presented. A polynomial-time algorithm is given that decides if an SC is a logical consequence of a set of SCs. Finally, another polynomial-time algorithm is given, which decides if there exists a database that contains a given path from a given class.

A typed, object-oriented database technology, equipped with appropriate declarative, temporal logic based executable constraints, is presented. The underlying object-oriented database type system is based on advanced features such as subtype, parametric and F-bounded polymorphism. A particularly distinctive feature of the type system is its associated type-safe reflection technology, which provides the flexibility required by database operators without sacrificing type safety. Strongly, and even statically typed, executable class specifications of a variety of standard database abstractions, both application-oriented and system-oriented, are presented in the paper, in order to demonstrate strate the applicability of the paradigm. The temporal logic basis of the constraint language has an execution model, as well as the minimal model semantics, and it allows complex, temporal behavioral patterns to be expressed. It is based on three tomporal operators: always, next time and some time, and rules that determine how these operators may be applied in temporal Horn clauses. Because of the object-oriented nature of the paradigm, the logic basis is also equipped with the equality predicate The proposed technology is intended to provide major advantages not only in managing appropriately complex application environments with temporal constraints, but also in providing more efficient (because of static type checking) and reliable database management systems. It offers the advantages of non-procedural data languages and the richness of a temporal object-oriented paradigm. It also leads to a powerful prototyping tool for structural and behavioral testing of complex, strongly typed object-oriented systems, prior to major procedural implementation efforts.

This paper discusses an object-oriented approach to temporal multimedia data modeling in OMEGA; a multimedia database management under development at the University of Library and Information Science. An object-orientated approach is necessary to integrate various types of heterogeneous multimedia data, but it has become clear that current object-oriented data models are not sufficient to represent multimedia data, particularly when they are temporal. For instance, the current object-oriented data models cannot describe objects whose attribute values change time-dependently. Also, they cannot represent temporal relationships among temporal multimedia objects. We characterize temporal objects as instances of a subclass of class TimeInterval with the temporal attributes and the temporal relationships. This temporal multimedia data model is designed upward compatible with the ODMG-93 standard object model. To organize a temporal multimedia database, a five temporal axes model for representing temporal multimedia objects is also introduced. The five temporal axes--an absolute, an internal, a quasi-, a physical, and a presentation time axis--are necessary to describe time-dependent properties of multimedia objects in modeling, implementing and use. A concrete example of this organization method is also illustrated.

In this paper, a pushdown automaton, with an infinite set of states as a partially ordered set (poset), is formulated, and its control problem of whether a given configuration can be transferred to another is discussed. For the controllability to be decidable, we take a condition the poset satisfies, that is, a condition that there are only finite number of states under the partial ordering between two given states. The control problem is decidable in polynomial time on condition the length of each pushed stack string is bounded by a constant in a given pushdown automaton. The motivation of considering the control problem comes up from the stack structure in implementing the SLD resolution deductions, in which the leftmost atom in each goal is selected and unified with some procedure name (that is, some head) of a definite clause, with the effect of the procedure name being replaced by the procedure bodies and unifications. Thus, the control problem is applied to describe the SLD resolution deductions of finite steps, by constructing a pushdown automaton model for a set of definite clauses, in which leftmost selection of atom in each goal forms a stack structure and substitutions affecting goals are interpreted as states. When constructing a pushdown automaton model for an SLD resolution deduction, algebraic properties of the idempotent substitution set, which are used in unifications, are examined and utilized. The quotient set of the idempotent substitution set per renamings is adopted to present the automaton model.

In general, multimedia files are much larger than ordinary text files because they consist of multiple monomedia. In order to process large multimedia files in real time, the file system must be able to store and access files efficiently. In th UNIX s5 file system, a multimedia file may be scattered into many disk blocks over the entire disk space, and accessing a multimedia file requires a considerable amount of time for random disk head movement. This paper proposes the internal structure of a multimedia file and its inode which is modified from UNIX s5 file system's. Also, we propose a mechanism for allocating and deallocating contiguous disk blocks for large multimedia files using the bitmap tree and compares its performance with that of the UNIX s5 file system. Our results show that the proposed mechanism reduces considerably the number of disk I/Os required to allocate and deallocate contiguous disk blocks. It also reduces the total access time for large multimedia files by approximately 95% due to the contiguous allocation of disk spaces.

A new method is developed to generate fuzzy rules from numerical data. This method consists of two algorithms: Algorithm 1 is used to identify structures of the given data set, that is, the optimal number of rules of system; Algorithm 2 is used to identify parameter of the used model. The former is belonged to unsupervised learning, and the latter is belonged to supervised learning. To identify parameters of fuzzy model, we developed a neural network which is referred to as Unsymmetrical Gaussian Function Network (UGFN). Unlike traditional fuzzy modelling methods, in the present method, a) the optimal number of rules (clusters) is determinde by input-output data pairs rather than by only output data as in sugeno's method, b) parameter identification of ghe present model is based on a like-RBF network rather than backpropagation algorithm. Our method is simple and effective because it integrates fuzzy logic with neural networks from basic network principles to neural architecture, thereby establishing an unifying framework for different fuzzy modelling methods such as one with cluster analysis or neural networks and so on.

The coherence in the time movement of the spectral vector sequence is modelled by a vector linear predictor. Such a model of the stop consonant transition is used for discrimination of the places of articulation of/ba/,/dha/,/da/, and/ga/. The effect of cross-channel correlation in giving improved recognition performance and also in reducing the time asymmetry of the predictive recognizer is studied. The high recognition score of vector model and the considerable differnce in the forward reverse score of the scalar model than a vecter model is highlighted in this study on a speech data of a set of four speakers.