1. A method of disambiguating user intent in conversational interactions for information retrieval, the method comprising: receiving information for a set of content items, each of the content items being associated with metadata that describes the corresponding content items; receiving information for structural knowledge, the structural knowledge showing relationships of multiple types among the content items; receiving information for a user preference signature, the user preference signature describing preferences of a user for at least one of (i) particular content items and (ii) metadata associated with the content items; receiving a first input from the user, the first input intended by the user to identify at least one desired content item; determining an ambiguity index of the first input; upon a condition in which the ambiguity index exceeds a first threshold value: upon a condition in which at least one of the structural knowledge, the user preference signature, a location of the user, and a time of the first input is available: determining a disambiguated first input based on the first input and the at least one of the structural knowledge, the user preference signature, the location of the user, and the time of the first input; upon a condition in which the at least one of the structural knowledge, the user preference signature, the location of the user, and the time of the first input is not available: presenting a question to the user; receiving a second input from the user in response to the question; and determining a disambiguated first input based on the first input and the second input; and selecting a subset of content items from the set of content items based on comparing the disambiguated first input and the metadata associated with the subset of content items; and upon a condition in which the ambiguity index does not exceed the first threshold value, selecting a subset of content items from the set of content items based on comparing the first input and the metadata associated with the subset of content items.