الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Information gathering is an essential process that users do as a daily routine. Up to lasts seventies the information environment was centralized and classical information retrieval techniques were used. By the beginning of eighties and within the incredible progress in communications and the overabundance increase in the size of networks, which are usually heterogeneous and distributed such as the Internet the information environment becomes distributed and retrieving relevant information requires much effort and time from users. The need for new techniques for distributed information retrieval appears. The thesis introduces a proposed system for distributed information retrieval by using mobile agent. Mobile agent is the recent methodology suggested in the last decade to be used in distributed information retrieval. Mobile agent is a software program that assists people and acts on their behalf. Mobile agent can migrate from machine to machine along the network until the completion of its task. The thesis realizes one of the most recent algorithms the Distributed Document Retrieval Agent. Two modifications are carried out on the Distributed Document Retrieval Agent algorithm to enhance its performance: 1?Adding a filter stage to exclude irrelevant documents. 2?Simplified model for searching LAN is derived. The proposed system was given a name Modified Distributed Document Retrieval Agent (MDDRA). Finally a comparison between the proposed system MDDRA and DDRA has made in order to test the performance of the proposed system. Moreover, the proposed system is compared with the FISH system in order to test the validity of the proposed system.