Information Retrieval Questions Medium
Query expansion is a technique used in information retrieval to improve the effectiveness of search queries by adding additional terms or concepts to the original query. This is done through query rewriting, which involves modifying the original query to include related terms or synonyms that may help retrieve more relevant documents.
The concept of query expansion recognizes that users may not always be able to express their information needs accurately or completely in a search query. By expanding the query, the retrieval system can capture a broader range of relevant documents that may not have been retrieved with the original query alone.
Query expansion can be performed in various ways. One common approach is to use a thesaurus or a synonym dictionary to identify synonyms or related terms for the query terms. These synonyms are then added to the original query to broaden its scope. For example, if the original query is "car," query expansion may add terms like "automobile" or "vehicle" to capture documents that use different terminology but are still relevant.
Another approach to query expansion is to analyze the top-ranked documents retrieved by the original query and extract additional terms or concepts from them. These terms are then added to the query to refine and expand its meaning. This technique, known as relevance feedback, leverages the assumption that the top-ranked documents are likely to contain relevant terms that were not present in the original query.
Query expansion using query rewriting aims to improve the recall and precision of information retrieval systems. By expanding the query with additional terms, it increases the chances of retrieving relevant documents that may have been missed with the original query. However, it is important to note that query expansion can also introduce noise or irrelevant documents if not carefully implemented. Therefore, it requires careful consideration and evaluation to ensure its effectiveness in improving retrieval performance.