1. A computer program product for automatically linking text to concepts in a knowledge base, the computer program product comprising: a non-transitory storage medium readable by a processing circuit and storing instructions for execution by the processing circuit to perform a method comprising: receiving, at a computer system, a plurality of text strings; building a conceptual index that links the text strings to the knowledge base, the building comprising for each of the text strings: selecting a plurality of data sources that correspond to at least a subset of the concepts in the knowledge base, the selecting based on contents of the text string; calculating, for each of the selected data sources, a probability that the text string is output by a language model built using the selected data source; calculating a probability that the text string is output by a generic language model that is not related to any particular concept in the knowledge base; calculating link confidence scores for each of the at least a subset of the concepts based on a differential analysis of the probabilities; and creating an entry in the conceptual index that includes a link between the text string and one of the concepts in the knowledge base, the creating based at least in part on a link confidence score of the concept being more than a first threshold value away from a prescribed threshold; generating a conceptual inverted index based on entries in the conceptual index, each entry of the conceptual inverted index corresponding to a different one of the concepts in the knowledge base and comprising pointers to at least a subset of text strings of the plurality of text strings linked to the concept in the conceptual index; receiving a query from an agent external to the computer system, the query specifying a concept in the knowledge base; processing the query by the computer system, the processing comprising searching the conceptual inverted index for the concept specified in the query and returning a pointer to a text string in an entry of the conceptual inverted index corresponding to the concept; and returning a set of documents to the external agent through the use of the conceptual inverted index, based on the received query.
4. The computer program product of claim 1 , wherein the calculating link confidence scores includes comparing the probabilities to a probability that the text string is contained in a generic data source that is not associated with any of the concepts in the knowledge base.