11. A method of determining a document score, which suggests a relevance of a document to a search query, the method comprising: receiving the search query; parsing the search query into a plurality of n-grams including a first n-gram, which includes a first weight quantifying an importance of the first n-gram to the search query; determining that the first weight satisfies a threshold weight criterion; identifying a first equivalent subject that is semantically similar to the first n-gram and that forms a subject group with the first n-gram, wherein the first equivalent subject is associated with an equivalent-subject score quantifying a confidence that the first equivalent subject and the first n-gram identify a same subject; determining a first-subject-group frequency comprised of both a first-subject frequency, which includes a number of times the first n-gram is found in the document, and a first-equivalent-subject frequency, which includes a number of times the first equivalent subject is found in the document; and calculating the document score of the document, wherein the document score is comprised of a first-subject-group score, and wherein the first-subject-group score is calculated by combining the first-equivalent-subject frequency with the equivalent-subject score, such that the first-equivalent-subject frequency is weighted based on a confidence that the first equivalent subject is semantically similar to the first n-gram.
11. A method of determining a document score, which suggests a relevance of a document to a search query, the method comprising: receiving the search query; parsing the search query into a plurality of n-grams including a first n-gram, which includes a first weight quantifying an importance of the first n-gram to the search query; determining that the first weight satisfies a threshold weight criterion; identifying a first equivalent subject that is semantically similar to the first n-gram and that forms a subject group with the first n-gram, wherein the first equivalent subject is associated with an equivalent-subject score quantifying a confidence that the first equivalent subject and the first n-gram identify a same subject; determining a first-subject-group frequency comprised of both a first-subject frequency, which includes a number of times the first n-gram is found in the document, and a first-equivalent-subject frequency, which includes a number of times the first equivalent subject is found in the document; and calculating the document score of the document, wherein the document score is comprised of a first-subject-group score, and wherein the first-subject-group score is calculated by combining the first-equivalent-subject frequency with the equivalent-subject score, such that the first-equivalent-subject frequency is weighted based on a confidence that the first equivalent subject is semantically similar to the first n-gram. 13. The method of claim 11 , wherein identifying an equivalent subject includes referencing an equivalent-subject datastore, which maintains a listing of equivalent subjects that have been identified as semantically similar to the first subject and the second subject.