Indexing in Search Engine
- 1. Context based Indexing in Search Engines using Ontology SHIKHA GUPTA ASSISTANT PROFESSOR ADVANCED EDUCATIONAL INSTITUTE www.advanced.edu.in
- 2. Flow of lesson 1. Search Engine 2. Indexing 3. Architecture 4. Various Components 5. Conclusion www.advanced.edu.in
- 3. What is Search Engine? Aim To provide most relevant documents to the users in minimum possible time. Major issue Granting efficient and fast accesses to the index www.advanced.edu.in
- 4. Existing architecture Index is built on the basis of the terms of the document. www.advanced.edu.in
- 5. Indexing Web Content Mining process Indexer Extracts a large amount of information which contain a given term www.advanced.edu.in
- 6. Inverted file (IF) okeeps account of number of occurrences of each term within every document, maintained in an index oSmall size occupancy oEfficient in resolution of keywords based queries www.advanced.edu.in
- 7. Term Based Index Less efficient due to two information retrieval problems: Polysemy (means a word has multiple meanings) Synonymy (means that multiple words having the same meaning). www.advanced.edu.in
- 8. Content Based Index Improve search result relevance. Use the concept of ontology. www.advanced.edu.in
- 9. Ontology Includes vocabulary for referring to the terms in that subject area and logical statements that describe the relationships among the terms. Example simple ontology for apple Set of concepts Capple = {apple, computer device, fruit, eatable, iphone} Set of relationships Rapple = {brandname_of (apple, iphone), type_of (apple, fruit)}. www.advanced.edu.in
- 11. Architecture of Context based Indexing Crawler gathers Web documents and stores them into a huge repository Every Web page has an associated ID number called document identifier, which is assigned whenever a new URL is parsed out of a web page Indexer takes the web pages collected by the spiders and parses them into a highly efficient index. www.advanced.edu.in
- 13. Description of various Components Repository of web page: Database containing set of documents collected by crawler. Indexer: After the documents have been gathered by the crawler, the indexer maintains an index of the documents which is in the form of posting lists that contain the term, document identifiers of the documents and other related information. www.advanced.edu.in
- 14. Preprocessing of document: It involves removal of stop words. A stop word is any word which has no semantic content. Common stop words are prepositions and articles. Thesaurus: It is a dictionary of words available on the world wide web from thesaurus.com which contains the words as well as their multiple meanings. www.advanced.edu.in
- 15. Context Repository: This is a database which contains the various contexts. New contexts derived from thesaurus are also stored in it. It maintains a database of several types of context data. Ontology Repository: This is a database of ontologies which contains the various relationships among objects in various domains. It contains various concepts with their relationships. www.advanced.edu.in
- 16. Context of the document: This context represents the theme of the document that has been extracted using context repository, thesaurus and ontology repository. Index: This is the final index that is constructed after extracting the context of the document. It have context as first field, term as next field and finally the document identifiers of the relevant documents. www.advanced.edu.in
- 17. Searcher: It receives user queries via the user interface and after searching the results in the index provides them to the user. Search Interface: It is that user interface through which user types the query along with the context specified. www.advanced.edu.in
- 18. CONCLUSION An indexing structure that can be constructed on the basis of the context of the document. Uses ontology for context based index building. Enables retrieval from index on the basis of context rather than keywords. Improves the quality of the retrieved results. Better performance of the existing system. www.advanced.edu.in
- 19. Shikha Gupta Assistant Professor Advanced Educational Institute Advanced Educational Institutions, 70 km Milestone, Delhi-Mathura Road, Dist. Palwal, Haryana-121105 +91–1275–398400, 302222 Shikha.0909@gmail.com www.advance.edu.in www.advanced.edu.in