955470
Improved Data Retrieval Using Semantic Transformation
Semantic query optimisation uses knowledge about properties of the data, represented as a set of subset descriptor rules, to transform a query into another form that can be executed in a more efficient manner but still yields the same result as the original query. Commonly this ’semantic knowledge’ in the form of rules is generated either during the query process itself or else is constructed in advance according to defined heuristics. Over a period of time the rule set may, therefore, become very large and the number of semantically equivalent queries that may be derived rises exponentially. Each rule use creates a new equivalent query. The problem is to identify one near optimal alternative query in a time that is minimal and also short relative to the overall query execution time. In this paper we propose a method for measuring the effectiveness of each rule and present a fast algorithm which selects the most cost effective transformations to directly yield the optimal alternative query. Experiments carried out on a large publicly available dataset show worthwhile savings using the approach.
34571067
Data Extraction from Web Database Query Result Pages via Tagsets and Integer Sequences
The World Wide Web is a collection of databases as well as web sites. Databases associated with web sites provide public access via query forms on web pages. They constitute an enormous repository of searchable data on an extremely diverse collection of subjects, ranging from multimedia collections through archives of subject-specific data to current information such as currency conversion or interest rates and news or weather reports. Many interesting and valuable Database Applications could be developed if these databases were easily and reliably accessible to programs. The difficulty in extracting data is the number of different web page formats and the tendency to change format suddenly. A rapid page analysis and wrapper creation system is needed to generate and maintain a data extraction facility for any required web sites. This important goal has been the subject of substantial recent research, modelling the web results page in various ways. The purpose of the current paper is to introduce a new method for rapid page analysis using the recurrence patterns of tagSet occurrence in the page.
6479052
Data Analysis for Query Processing
Data analysis is needed in connection with query processing, to produce data summary information in the form of rules or assertions that allow semantic query optimisation or direct query answering without consulting the data itself. The goal of an intelligent analyser in this context is to produce robust rules, stable in the presence of data changes, which allow easy rule maintenance as data changes, and provide rapid query reformulation, refutation or answering. It must also limit the rule set to rules useful for query processing.
12408680
Utilising Multiple Computers in Database Query Processing and Descriptor Rule Management
A fundamental problem to be solved in systems that derive rules from database tables to use in query optimisation is the workload involved. If the data server has to do the work it can interfere with query processing and cause slower query answering, which is the opposite of the required effect. This paper reports our investigation of the use of multiple workstations in the same local network as the data server to derive and maintain sets of rules describing data subsets. These rules are used in query optimisation. In a local area network of workstations, one computer accepts SQL queries and data manipulation commands from networked clients. This computer provides an interface to one or more database management systems located on computers in the network. It uses a collection of subset-descriptor rules for query reformulation before forwarding the semantically optimised query. It manages a set of workstations in the network, to derive and maintain the rules. The workstations are ordinary networked computers whose spare computing capacity is utilised by spawning background programs on them.
10379830
Extended Query Answering Using Integrity Rules
The conventional use of databases is commonly restricted to the retrieval of factual data in the form of tuples or records. However most databases also contain metadata in the form of integrity rules which can provide a rich source of additional information not normally available to the user. Integrity rules define what data values and relationships may exist within the database and so their interrogation can provide answers as to whether a certain database state is possible. Our paper describes how this may be achieved and specifies a formal approach to implementing such an enquiry system.
6242831
Distributing the Derivation and Maintenance of Subset Descriptor Rules
This draft paper describes a solution to the rule maintenance problem for data descriptor rules derived from data that may subsequently change. The method utilises any available computers in the local area network, to derive and maintain rule sets.
5441653
Integrating targeted cycle-time reduction into the capital planning process
This paper describes the development and application of an integrated static capacity and dynamic simulation analysis methodology for purchasing equipment capacity. The goal of the study is to address targeted cycle time objectives in a start up recording head wafer manufacturing facility at Seagate Technology, Minneapolis, MN. The short product cycle time, coupled with the competitive nature of the disc drive industry, has made cycle time reduction one of the most important objectives of production capacity planning. This paper describes an equipment procurement strategy in which static capacity analysis is used to identify an initial equipment set with a low slack capacity variable on each tool group. Simulation analysis is then used to identify the critical tool groups that contribute to cycle time delays. The Seagate Industrial Engineering team used the simulation analysis tool Factory Explorer(R) from Wright, Williams and Kelly to perform the cycle time reduction analysis. This targeted approach is compared to the traditional static capacity planning approach of globally applying reserve capacity buffers of 20% or more to achieve the same cycle time reduction goal. Overall, the targeted approach has proven to be efficient in terms of minimizing capital equipment expenditures and also effective on the factory floor.
6721869
A Performance Study of Deployment Factors in Wireless Mesh Networks
We present a measurement-parameterized performance study of deployment factors in wireless mesh networks using three performance metrics: client coverage area, backhaul tier connectivity, and fair mesh capacity. For each metric, we identify and study topology factors and architectural features which strongly influence mesh performance via an extensive set of Monte Carlo simulations capturing realistic physical layer behavior. Our findings include: (i) A random topology is unsuitable for a large-scale mesh deployment due to doubled node density requirements, yet a moderate level of perturbations from ideal grid placement has a minor impact on performance. (ii) Multiple backhaul radios per mesh node is a cost-effective deployment strategy as it leads to mesh deployments costing 50% less than with a single-radio architecture, (iii) Dividing access and backhaul connections onto two separate radios does not use the second radio efficiently as it only improves fair mesh capacity 40% to 80% for most users. This is in contrast to using the second radio to move half the user population to a new network operated on the second radio. This work adds to the understanding of mesh deployment factors and their general impact on performance, providing further insight into practical mesh deployments.
2266734
Procedures for Integrating Knowledge in a Speech Understanding System
T h i s paper d e s c r i b e s t h e p r o c e d u r e s f o r i n t e g r a t i n g knowledge f rom d i f f e r e n t s o u r c e s i n t h e SRI speech u n d e r s t a n d i n g s y s t e m . A language d e f i n i t i o n sys tem c o o r d i n a t e s — a t t h e ph rase l e v e l — i n f o r m a t i o n f rom s y n t a x , s e m a n t i c s and d i s c o u r s e i n t h e cou rse o f t h e i n t e r p r e t a t i o n o f a n u t t e r a n c e . The sys tem e x e c u t i v e uses t h e s e c o n t e x t u a l c o n s t r a i n t s i n a s s i g n i n g p r i o r i t i e s t o a l t e r n a t i v e i n t e r p r e t a t i o n s , c o m b i n i n g t o p d o w n , b o t t o m u p , and b i d i r e c t i o n a l s t r a t e g i e s a s r e q u i r e d E x p e r i m e n t a l r e s u l t s t h a t d e m o n s t r a t e t h e e f f e c t i v e n e s s o f c o n t e x t c h e c k i n g a r e d i s c u s s e d .
40861592
Definability and Decision Problems in Arithmetic
In this paper, we are concerned with the arithmetical definability of certain notions of integers and rationals in terms of other notions. The results derived will be applied to obtain a negative solution of corresponding decision problems. In Section 1, we show that addition of positive integers can be defined arithmetically in terms of multiplication and the unary operation of successor S (where Sa = a + 1). Also, it is shown that both addition and multiplication can be defined arithmetically in terms of successor and the relation of divisibility | (where x|y means x divides y ).
28156050
An Introduction to Hyperarithmetical Functions