search engine techniques

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Terminology Search Engine Web crawler

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Search Engine A Web search engine is a tool or a program designed to search for information on the WWW on the basis of specified keywords and returns a list of the documents where the keywords were found. The search results are usually presented in a list and are commonly called hits. The information may consist of webpages, images, information and other types of files

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Web Crawler A Web crawler is a computer program that browses the WWW in a methodical, automated manner. Other terms for Web crawlers are  ants, automatic indexers, bots, and worms or Web spider, Web robot, Web scutter This process is called Web crawling or spidering.

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Why search engine ??? “ Internet environment is having huge amount of textual information yet it was just impossible to find anything ” And thus there is a need of a program or a tool that keep track of this all information and this is what the SEARCH ENGINE provides.

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Search Engine Working A search engine operates, in the following order 1. Web crawling :- Document Gathering step 2. Indexing :- Document Arrangement Step 3. Information Extraction and Storing in DB 4.User Request :- Request for specific “keyword” 5. Searching :- Query Building and Execution 6.Response to user

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History Of Search Engine

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Keyword searching Most common form of text search on the Web “Keyword” specified by the user is searched Those keywords would actually tell a user something about the subject and content of this page. It's up to the search engine to determine the type keyword They may refer to the words specified as the title of the documents or their first line content for “MATCHING ” purpose

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Keyword searching Problems with keyword searching Same spelled KEYWORD Stemming Problem Synonym Problem

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Stemming Problem BIG_ Search Engine XYZ GO! Should I check for the “BIGGER” “Biggest”……..??

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Synonym Problem BIG_ Search Engine XYZ GO! I am not going to return the documents having synonym of heart , “CARDIAC”

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Same spelled KEYWORD BIG_ Search Engine XYZ GO! It will return…………..the following Most of these are IRRELEVANT to the user , Also the problem of CASE SENSITIVITY

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Refined Searching ADVANCED SEARCH “Criteria of searching” is given by the user Uses BOOLEAN operators Allow the user to Search entire phrase , Field Searching,  specify what form he would like his results to appear in , restrict his search to certain fields on the internet (i.e., usenet or the Web)

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BOOLEAN operators Boolean AND FCC AND WIRELESS AND COMMUNICATION Boolean OR FCC OR WIRELESS OR COMMUNICATION

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Boolean AND NOT BOOLEAN operators Boolean +/- : + AND - AND NOT

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Phrase Search It will search the entire “Phrase” , “San Francisco Art”

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Field Search Most effective technique for narrowing results A web page is has a number of fields, such as title, domain, host, URL, and link. Searching effectiveness increases as you combine field searches with phrase searches and Boolean logic. +title:“Thailand" - Image will return the indicated result

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Concept-based searching Semantic Search Concept-based search systems try to determine what user mean Returns hits on documents that are "about" the subject/theme user exploring, even if the words in the document don't precisely match the words you enter into the query.

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Concept-based searching Builds clustering systems ,and note the no of frequencies occurring in the document The higher the frequency , the higher the ranking of the document Example

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Concept-based searching Search Engine XYZ GO! It will return the documents related to medical\health science

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Concept-based searching Search Engine XYZ GO! A concept-oriented search engine returns hits on the subject of romance.

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Popularity The chart shows the percentage of online searches done by US home and work web surfers in July 2006 that were performed at a particular search engine

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Current Status The graph shows how the share of searches has changed over the past few months, for those search sites with a share of 5 percent or higher:

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Thank You!!!!!!!!!!!Happy Searching……..