Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for receiving queries, and for each received query: receiving data indicating resources identified by a search operation as being responsive to the query, wherein the search operation scores each of the resources based, in part, on features of the resource and the query, selecting a subset of the resources, determining, from the subset of resources and for each of the features of the resources and the query, an impact measure that measures the impact of the feature on the ranking of the resources that belong to the subset, adjusting the search operation based on the respective impact measures, and initiating the search operation to re-score the resources in the subset of resources based, in part, on the adjustment and to rank the subset of resources according to a second order that is different from the first order.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, re-ranking resources for categorical queries. In one aspect, a method includes receiving queries, and for each received query: receiving data indicating resources identified by a search operation as being responsive to the query and ranked according to a first order, each resource having corresponding search score by which the resources are ranked in responsiveness to the query and determining whether a proper subset meets a quality condition based on a quality measure that is indicative of the quality of the resources in the proper subset and independent of search scores of the resources for received query. For each query for which the proper subset meets the quality condition, determining a quality score for each resource in the proper subset and re-ranking the resources in the proper subset according to their respective quality scores.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for identifying languages that are relevant to resources. In one aspect, a method includes selecting in a data processing apparatus a first resource; accessing click data that identifies, for each of a plurality of requests for the first resource, a respective search engine user interface from which the request was received; identifying a search engine user interface language for each of the plurality of requests based on the click data; determining a respective language relevance score for the first resource for each identified search engine user interface language; and selecting one or more languages as being relevant to the first resource based on the language relevance scores.

Abstract: Methods, systems, and apparatus, including computer program products, for identifying navigational resources for queries. In an aspect, a candidate query in a query sequence is selected, and a revised query subsequent to the candidate query in the query sequence is selected. If a quality score for the revised query is greater than a quality score threshold and a navigation score for the revised query is greater than a navigation score threshold, then a navigational resource for the revised query is identified and associated with the candidate query. The association specifies the navigational resource as being relevant to the candidate query in a search operation.

Abstract: Methods, systems, and apparatus, including computer program products for structured content ranking. In an aspect, a method determines a service requirement from terms of a query, the service requirement being one of a plurality of service requirements fulfilled by databases; determines, for each of the databases, a service requirement score for the database, the service requirement score being a measure of an ability of the database to fulfill the service requirement; selects databases based on the service requirement scores; generates data responsive to the service requirement based on the terms of the query and one or more of the selected databases; and generates, from the data identifying resources that are determined to be responsive to the query and from the data responsive to the service requirement, search results that include first search results that each identify a corresponding resource that was determined to be responsive to the query.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for ranking search results. One method includes ranking web objects in response to a search query to generate a global ranking based on a relevance of each web object to the search query and a relative authority of each web object compared to other web objects in the plurality of web objects, each web object including a web page in a corresponding website that includes a plurality of web pages; ranking the plurality of web pages corresponding to each website based on onsite ranking criteria to generate an onsite ranking; generating a combined ranking for each web page based on a combination of the global ranking of the web object that includes the web page and the onsite ranking of the web page; and presenting web pages responsive to the search query based on the combined rankings.

Abstract: Methods, systems, and apparatus for selecting geographic areas of interest for a query. A method includes for each query stored in search log data, determining an origin location for each occurrence of the query, determining a content location for each occurrence of the query, for each of a plurality of catchment areas, determining catchment area matches for the query based on the origin location of each occurrence of the query and the content location of the occurrence of the query, determining, for each catchment area, a catchment area score that is indicative of an interest level for the catchment area for a query, the determination based on a number of catchment area matches for the catchment area for the query and selecting, for the query and based on the catchment area scores for the catchment areas, one of the catchment areas as a selected catchment area for the query.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for correcting potentially inaccurate terms in queries. In an aspect, a search system determines that an original query includes a potentially inaccurate term. The determination is made on the basis that the term of the original query meets an inaccuracy criterion. Derivative queries are generated from the original query. Each derivative query does not include the potentially inaccurate term. For each derivative query resources that are determined to be responsive to the derivative query are determined, and from the resources, a corrected term is determined. The corrected term is substituted for the potentially inaccurate term, and a search operation that uses the corrected query as input is performed.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for servicing search queries. In one aspect, a method includes determining that a general search query is a locally significant query for a user location that is associated with the user general search query. In turn, a local search query is generated using the general search query and a location phrase representing the user location. A set of set of general search results responsive to the general search query and a set of local search results responsive to the local search query are requested. A final set of search results responsive to the search query are selected. The final set of search results include at least one search result that is included in the set of local search results, and is not included in a pre-specified quantity of highest ranking search results from the set of general search results. Data that cause presentation of the final set of search results are provided.

Abstract: Methods, systems, and apparatus, including computer program products for structured content ranking. In an aspect, a method determines a service requirement from terms of a query, the service requirement being one of a plurality of service requirements fulfilled by databases; determines, for each of the databases, a service requirement score for the database, the service requirement score being a measure of an ability of the database to fulfill the service requirement; selects databases based on the service requirement scores; generates data responsive to the service requirement based on the terms of the query and one or more of the selected databases; and generates, from the data identifying resources that are determined to be responsive to the query and from the data responsive to the service requirement, search results that include first search results that each identify a corresponding resource that was determined to be responsive to the query.

Abstract: Methods, systems, and apparatus for selecting geographic areas of interest for a query. A method includes for each query stored in search log data, determining an origin location for each occurrence of the query, determining a content location for each occurrence of the query, for each of a plurality of catchment areas, determining catchment area matches for the query based on the origin location of each occurrence of the query and the content location of the occurrence of the query, determining, for each catchment area, a catchment area score that is indicative of an interest level for the catchment area for a query, the determination based on a number of catchment area matches for the catchment area for the query and selecting, for the query and based on the catchment area scores for the catchment areas, one of the catchment areas as a selected catchment area for the query.

Abstract: One embodiment of the present invention provides a system for detecting correlations between terms. During operation, the system identifies one or more lists contained in one or more documents and identifies two terms co-occurring in the lists. The system further determines a correlation between the co-occurring terms, and places the co-occurring terms in a correlated-pair list based on the correlation.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for identifying languages that are relevant to resources. In one aspect, a method includes selecting in a data processing apparatus a first resource; accessing click data that identifies, for each of a plurality of requests for the first resource, a respective search engine user interface from which the request was received; identifying a search engine user interface language for each of the plurality of requests based on the click data; determining a respective language relevance score for the first resource for each identified search engine user interface language; and selecting one or more languages as being relevant to the first resource based on the language relevance scores.

Abstract: One embodiment of the present invention provides a system that considers lexical synonyms for terms while processing a query. During operation, the system receives a query containing one or more terms. Next, the system identifies one or more lexical synonyms for the one or more terms. The system then generates an altered query using the one or more lexical synonyms and processes the altered query to produce search results.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for obtaining search results from high-quality sites. One of the methods includes receiving data identifying first resources that are responsive to a first query. If at least a first threshold number N of top-ranked first resources are located on sites previously identified as low quality sites, a second query and data identifying second resources that are responsive to the second query are obtained, wherein at least a second threshold number M of top-ranked second resources are located on sites previously identified as being high-quality sites. Search results are provided in response to the first query, wherein the search results identify one or more of the first resources and also identify a particular second resource of the second resources.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for retrieving documents. One of the methods includes receiving a search query that includes a first query term and an adjacent, second query term, and a substitute term for the first query term. A determination is made that the first query term and the substitute term satisfy one or more predetermined criteria and that a resource does not include the first query term. The resource is selected to be scored only if the substitute term occurs adjacent to the second term in the resource.

Abstract: Methods, systems, and apparatus for selecting geographic areas of interest for a query. A method includes for each query stored in search log data, determining an origin location for each occurrence of the query, determining a content location for each occurrence of the query, for each of a plurality of catchment areas, determining catchment area matches for the query based on the origin location of each occurrence of the query and the content location of the occurrence of the query, determining, for each catchment area, a catchment area score that is indicative of an interest level for the catchment area for a query, the determination based on a number of catchment area matches for the catchment area for the query and selecting, for the query and based on the catchment area scores for the catchment areas, one of the catchment areas as a selected catchment area for the query.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for correcting potentially inaccurate terms in queries. In an aspect, a search system determines that an original query includes a potentially inaccurate term. The determination is made on the basis that the term of the original query meets an inaccuracy criterion. Derivative queries are generated from the original query. Each derivative query does not include the potentially inaccurate term. For each derivative query resources that are determined to be responsive to the derivative query are determined, and from the resources, a corrected term is determined. The corrected term is substituted for the potentially inaccurate term, and a search operation that uses the corrected query as input is performed.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for ranking search results. One method includes ranking web objects in response to a search query to generate a global ranking based on a relevance of each web object to the search query and a relative authority of each web object compared to other web objects in the plurality of web objects, each web object including a web page in a corresponding website that includes a plurality of web pages; ranking the plurality of web pages corresponding to each website based on onsite ranking criteria to generate an onsite ranking; generating a combined ranking for each web page based on a combination of the global ranking of the web object that includes the web page and the onsite ranking of the web page; and presenting web pages responsive to the search query based on the combined rankings.

Abstract: One embodiment of the present invention provides a system that uses a known set of related terms to identify additional related terms in different languages. During operation, the system receives two terms that are known to be related. The system translates these two non-synonym terms into a given language, and then adds the translations of the two related terms to a list of known related pairs.