2. The method according to claim 1 , wherein the change-based feature of said each word in the first query relative to the second query comprises: a first change-based feature, used to indicate whether said each word in the first query relative to the second query is a new word; a second change-based feature, used to indicate a change of a position of said each word in the first query relative to a position of said each word in the second query; a third change-based feature, used to indicate a change of a part-of-speech of said each word in the first query relative to a part-of-speech of said each word in the second query; a fourth change-based feature, used to indicate a change of a syntactic class of said each word in the first query relative to a syntactic class of said each word in the second query; or a fifth change-based feature, used to indicate a change of punctuation marks at both ends of said each word in the first query relative to punctuation marks at both ends of said each word in the second query.
1. A stop word identification method, wherein the method is executed by an information retrieval system running on a computing device and comprises: receiving a first query comprising a plurality of words; acquiring a session identifier (ID) corresponding to the first query; acquiring, according to the session ID, a second query that belongs to a same session as the first query; determining that the first query and the second query forms a query chain, wherein the second query meets at least one of the following conditions to form the query chain with the first query: a length of a longest common clause of the first query and the second query is greater than a first threshold; or a minimum quantity of operations required for converting the first query into the second query is less than a second threshold; or the first query is mapped to a first vector, the second query is mapped to a second vector, and an included angle or a distance between the first vector and the second vector is less than a third threshold; and based on the determination: acquiring a change-based feature of each word in the first query relative to the second query; and identifying a stop word in the first query according to the change-based feature of said each word in the first query relative to the second query.