8. A method performed by data processing apparatus, the method comprising: one or more computers configured to perform operations comprising: storing a respective plurality of category-location relevance scores for each location of a plurality of geographic locations, wherein each category-location relevance score for each location estimates a relevance of a respective category to the location, and wherein a category-location relevance score is based on a plurality of category-entity-location relevance scores for a plurality of entities associated with the category at the location, wherein storing a category-location relevance score for a location comprises storing a plurality of Taylor coefficients for a function at the location, wherein an evaluation of the function for a location provides a category-location relevance score for the category, and wherein an evaluation of the function at a location is determined by evaluating a sub-function for each of the plurality of entities, and wherein an evaluation of the sub-function for an entity provides a category-entity-location relevance score for the entity and the location; determining a first category-location relevance score for a first geographic location that is not one of the plurality of geographic locations, including: selecting a second geographic location in the plurality of geographic locations, and calculating the first category-location relevance score based on a second category-location relevance score for the second geographic location and a physical distance between the first geographic location and the second geographic location; and selecting an item from a plurality of candidate items using the first category location relevance score, wherein each candidate item is associated with a respective category, and wherein selecting the item comprises: ranking the plurality of candidate items using the first category location relevance score, and selecting a highest ranked candidate item.
8. A method performed by data processing apparatus, the method comprising: one or more computers configured to perform operations comprising: storing a respective plurality of category-location relevance scores for each location of a plurality of geographic locations, wherein each category-location relevance score for each location estimates a relevance of a respective category to the location, and wherein a category-location relevance score is based on a plurality of category-entity-location relevance scores for a plurality of entities associated with the category at the location, wherein storing a category-location relevance score for a location comprises storing a plurality of Taylor coefficients for a function at the location, wherein an evaluation of the function for a location provides a category-location relevance score for the category, and wherein an evaluation of the function at a location is determined by evaluating a sub-function for each of the plurality of entities, and wherein an evaluation of the sub-function for an entity provides a category-entity-location relevance score for the entity and the location; determining a first category-location relevance score for a first geographic location that is not one of the plurality of geographic locations, including: selecting a second geographic location in the plurality of geographic locations, and calculating the first category-location relevance score based on a second category-location relevance score for the second geographic location and a physical distance between the first geographic location and the second geographic location; and selecting an item from a plurality of candidate items using the first category location relevance score, wherein each candidate item is associated with a respective category, and wherein selecting the item comprises: ranking the plurality of candidate items using the first category location relevance score, and selecting a highest ranked candidate item. 10. The method of claim 8 , wherein the category is a business category and the plurality of entities is a plurality of businesses in the business category, and wherein each category-entity-location relevance score for a business is based on a physical distance between an address of the business in the category and a geographic location.