3. The method as claimed in claim 1 further comprising classifying, by the processor, the expression into one of a discussion, learning, and unlearning.
3. The method as claimed in claim 1 further comprising classifying, by the processor, the expression into one of a discussion, learning, and unlearning. 9. The method as claimed in claim 3 , wherein the unlearning comprises: obtaining a list of previously taught facts from a user graph; receiving a selection of at least one fact for being deleted from the user graph, wherein the at least one fact is one of incorrect, redundant, and irrelevant; and deleting the at least one fact from the user graph.