Google currently uses stemming, as described by the company itself:
Word variations (stemming)
Google now uses stemming technology. Thus, when appropriate, it will search not only for your search terms, but also for words that are similar to some or all of those terms. If you search for pet lemur dietary needs, Google will also search for pet lemur diet needs, and other related variations of your terms. Any variants of your terms that were searched for will be highlighted in the snippet of text accompanying each result.
A statistical model patent has been applied for that would be even more complex. If question and answer pairs are closely examined, one after another by the thousands, and also query and snippet pairs, a pattern may emerge that can shed light on what people search for and how they phrase their queries. Results that have been selected and viewed more frequently and/or longer by people who searched using those query terms may indicate that those snippets are more relevant for the query term searched with.
Phrase and paraphrase pairs such as “How to ship a dog” or “How to transport a dog” are phrases that can be translated easily from one language to another and back again without losing the key meaning. Synonyms are a large part of the concept behind search query anticipation.
Misspellings are also being addressed – Google will often ask you if you meant something else, provide a mixed batch of results, or simply pre-empt your query and provide the results it is fairly certain you are looking for. A search for madona will in all likelihood bring up a blend of results ranging from famous art to the pop star.
If you search for a query that includes the word “automobile” and the word “car” produces very relevant results as well, then that kind of query expansion is bound to become more popular. Expect to see more ‘stemming’ and expansion of query strings in 2009.
Tags: expanded results, queries, search