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Analysis of Signature Generation Schemes for Multiterm Queries In Partitioned Signature File Environments
Get PDFOur analysis explores the performance of three superimposed signature generation schemes as they are applied to a dynamic sigrtature file organization based on linear hashing: Linear Hashing with Superinzposed Signatures (LHSS). First scheme (SM) allows all terms set the same number of bits whereas the second and third methods (MMS and MMM) emphasize the terms with hlgh discriminatory power. In addition, M Mco nsiders the probaOiZity distribution of the number of query terms. The main contribution of the study is the combination of signature generation and signature file organization concepts together
with the relaxation of the single term query and uniform frequency assumptions. The derivation of the performance evaluation formulas are provided as well as the analysis of various experimental settings. Results indicate that MMM outperforms the others as terms become more distinctive in their discriminatory power. MMM accomplishes the highest savings in retrieval eficiency for the high query weight case. We also discuss the applicability of the derivations to other partitioned signature organizations providing a detailed analysis of Fixed Prefix Partitioning (FPP) as an example. Finally, an appro.ximate perfortnance evaluation formula that works for both FPP and LHSS is modijied to account for the multiterm case
Tool for Structural Testing of Rule-based System
Get PDFTraditional software testing techinque are useful in testing some components of the expert systems, such as the interference engine. However, there is a need for the development of a testing method that tests the structure in a rule-based system. This testing method should be computationally effective, provide a reasonable level of coverage of the rule base, and be independent of the inference engine [KIPER92]. In the article Structural testing of Rule-based Expert Systems by Dr. JAmes D. Kiper, the logical path graph (LPG) method was chosen as a practical testing method for an expert system. However, the logical path graph algorithm developed in that paper requires further investigation by application to large rule bases. This need has resulted in the development of a computer tool called Graptool. The Graptool software, that has been created, was based on the logical path algorithm and was written in the C language. This tool reads the CLIPS rule-based expert system as a text file, and constructs a listing that represents the structure of the rule base
Analysis of Multiterm Queries in Partitioned Signature File Environments
Get PDFThe concern of this study is the signature files which are used for information storage and retrieval in both formatted and unformatted databases. The analysis combines the concerns of signature extraction and signature file organization which have usually been treated as separate issues. Both the uniform frequency and single term query assumptions are relaxed and a comprehensive analysis is presented for multiterm query environments where terms can be classified based on their query and database occurrence frequencies. The performance of three superimposed signature generation schemes is explored as they
are applied to a dynamic signature file organization based on linear hashing: Linear Hashing with Superimposed Signatures (LHSS). First scheme (SM) allows all terms set the same number of bits regardless of their discriminatory power whereas the second and third methods (MMS and MMM) emphasize the terms with high query and low database ooccurrence frequencies. Of these three schemes, only MMM takes the probability distribution of the number of query terms into account in finding the optimal mapping strategy. The main contribution of the study is the derivation of the performance evaluation formulas which is provided together with the analysis of various experimental
settings. Results indicate that MMM outperforms the other methods as the gap between the discriminatory power of the terms gets larger. The absolute value of the savings provided by MMM reaches a maximum for the high query weight case. However, the extra savings decline sharply for high weight and moderately for the low weight queries with the increase in database size. The applicability of the derivations to other partitioned signature organizations is discussed and a detailed analysis of Fixed Prefix Partitioning (FPP) is provided as an example. An approximate formula that is shown to estimate the
performance of both FPP and LHSS within an acceptable margin of error is also modified to account for the multiterm case
"PanaeaMud An Online, Object-oriented Multiple User Interactive Geologic Database Tool"
Get PDFThis paper provides an overview of the design, development, and use of the PangaeaMud Database System. Section I gives an introduction to pertinent concepts and discusses previous work in the area. Section I1 is devoted to the non-technical aspects of the system. A brief user's view of the system is provided, along with discussion of the internal environment utilities.
Section I11 illustrates the workings of the system from the programmer's viewpoint and contains information on the main entity relationships within the database and their implementation
A Simulation of Rapid Evolution: Its Development in the Object-Oriented Paradigm
Get PDFThis project centered around an event in population
genetics, the modeling necessary to explain it, and the way that
the object-oriented paradigm influenced the implementation of the model. This paper is divided into three major sections which echo the three lines of investigation in the project. The first section is a summary of the concepts and terminology of genetics necessary for the understanding of what follows. The second is a description of the model and its results. The third is a report on the process of moving the software from a procedural language to an object-oriented one
Implementation of the Interview Scheduling System for Miami University's Career Planning and Placement Office
Get PDFThis project is an extension of systems analysis and design cavered in two classes - SAN 4721572 (Analysis of Infcwmation Systems) and SAN 4751575 (Structured Design and Implementation). My implementation involved work in the areas of integrating a subset of the system, designing a multiuser accessing means, investigating database security, implementing
dynamic calls, setting-up a database load facility, and researching laser printers and forms software. The integration involved getting the system to an operational state as opposed
to a production state. Multiuser access to the system will be permitted to about 2600 Seniors and accounting Juniors. The students will be permitted to access the system simultaneously,
and SQL will provide the concurrency control. The database security will be upheld by offering authority privilege to the program instead of the users. Dynamic calls will be used to maintain a reasonable virtual machine size. A database load facility will be used by the DBA at the beginning of every year to load demographic data pertaining to students, The standard resumes will be printed by the CPPO and that will require a new laser and a forms software. Research has been completed for various lasers and forms software, and a recommendation is given. The final portion of the paper presents some of the benefits that 1 have obtained while working on this project
An Expert System Shell Performing the Generic Task of Hierarchical Classification
Get PDFAny expert system shell that performs with the generic task of hierarchical classificiation must deal explicitly with the issues of knowledge representations, control strategies, inductive learning, and ways of handling uncertainty, ambiguity, and contradictions. This resesarch is mainly concerned about the creation of the expert system shell HICLASS. Aspects crucial to this task are challenged from btoh a theoretical and an implementational point of view.
The principles of generic tasks and hierarchical classification are described. Important concepts of HICLASS are introducted, followed by a detailed description of the knowledge representation and local control strategies developed for the system, including a discussion of special problems and respective solutions. IT is described how HICLASS handles uncertainty. Important issues like concluding values, explanation, learning, incorporating metaknowledge, and the global control strategy of HICLASS are discussed. Then, the actual implementation of the table editor HIEDIT as well as HICLASS is described in detail. It is show that HICLASS is a genuine tool for the generic task for hierarchical classification. The system is compared to two well-known tools for hierarchical classification. Using the ideas raised for HICLASS, the development of a hierarchical hypothesis matcher, HIHYPO, is proposed. Essential features of HIHYPO are introducted. A theoretic overview about algorithms for inductive learning is followed by the description of an inductive learning algorithm developed for HIHYPO. Appendix B provides an overview about software engineering methods, and a discussioin about methods actually used to create the HICLASS package. In Appendix C, the definitions of all modules developed for the package are shown
Signature Files: An Integrated Access Method for Formatted and Unformatted Databases
Get PDFThe signature file approach is one of the most powerful information storage and retrieval techniques which is used for finding the data objects that are relevant to the user queries. The main idea of all signature based schemes is to reflect the essence of the data items into bit pattern (descriptors or signatures) and store them in a separate file which acts as a filter to eliminate the non aualifvine data items for an information reauest. It provides an integrated access method for both formattid and formatted databases. A complative
overview and discussion of the proposed signatnre generation methods and the major signature file organization schemes are presented. Applications of the signature techniques to formatted and unformatted databases, single and multiterm query cases, serial and paratlei architecture. static and dynamic environments are provided with a special emphasis on the multimedia databases where the pioneering prototype systems
using signatnres yield highly encouraging results