15-09-2017, 03:47 PM
Information retrieval (IR) is the activity of obtaining information resources relevant to a need for information from a collection of information resources. Searches can be based on full text or other content-based indexing. Information retrieval is the science of finding information in a document, searching for documents themselves, and also finding metadata describing data, and for databases of texts, images or sounds.
Automated information retrieval systems are used to reduce what has been termed information overload. Many universities and public libraries use IR systems to provide access to books, magazines, and other documents. Web search engines are the most visible IR applications. An information retrieval process begins when a user enters a query into the system. Queries are formal declarations of information needs, for example search engines in web search engines. In information retrieval, a query does not uniquely identify a single object in the collection. Instead, several objects may match the query, perhaps with varying degrees of relevance.
An object is an entity that is represented by information in a collection of content or a database. User queries are compared to the database information. However, unlike the classic SQL queries of a database, in retrieving information the returned results may or may not match the query, so the results are usually sorted. This ranking of results is a key difference in the search for information retrieval compared to database search.
Depending on the application, the data objects may be, for example, text documents, images, audio, mind maps or videos. Often, the documents themselves are not saved or stored directly in the IR system, but are represented on the system using replacement documents or metadata.
Most IR systems calculate a numerical score on how each object in the database matches the query and sorts the objects according to this value. The top ranking objects are then shown to the user. The process can then be iterated if the user wants to refine the query.
Automated information retrieval systems are used to reduce what has been termed information overload. Many universities and public libraries use IR systems to provide access to books, magazines, and other documents. Web search engines are the most visible IR applications. An information retrieval process begins when a user enters a query into the system. Queries are formal declarations of information needs, for example search engines in web search engines. In information retrieval, a query does not uniquely identify a single object in the collection. Instead, several objects may match the query, perhaps with varying degrees of relevance.
An object is an entity that is represented by information in a collection of content or a database. User queries are compared to the database information. However, unlike the classic SQL queries of a database, in retrieving information the returned results may or may not match the query, so the results are usually sorted. This ranking of results is a key difference in the search for information retrieval compared to database search.
Depending on the application, the data objects may be, for example, text documents, images, audio, mind maps or videos. Often, the documents themselves are not saved or stored directly in the IR system, but are represented on the system using replacement documents or metadata.
Most IR systems calculate a numerical score on how each object in the database matches the query and sorts the objects according to this value. The top ranking objects are then shown to the user. The process can then be iterated if the user wants to refine the query.