Method for training information retrieval model based on weak-supervision and method for providing search result using such model

An apparatus for providing a user with a search result corresponding to a query input by the user from a corpus including a plurality of passages, comprising:

• at least one processor;
• and
• at least one memory for storing computer-executable instructions,
• the computer-executable instructions stored in the at least one memory that are operable, when executed by the at least one processor, to perform operations including:
• (a) retrieving, by an information retrieval model based on an unsupervised learning, N passages corresponding to the query from the corpus;
• (b) re-ranking, by an artificial intelligence based information retrieval model trained by a weak-supervision methodology, the N passages retrieved in step (a) based on the query;
• and,
• (c) outputting a list of search results corresponding to the passages re-ranked in step (b),
• wherein each passage of the corpus is a part of each document of the document corpus including a plurality of documents to be searched, and
• wherein the artificial intelligence based information retrieval model trained by the weak-supervision methodology is trained based on pseudo-labels which are generated by using the plurality of passages included in the corpus and a pseudo-query generated from each passage, said pseudo-query generated by an information retrieval model based on unsupervised learning including the information retrieval model that is used in the step (a).