1. A method for linking textual and physical concepts, comprising: extracting candidate phrases from a knowledge base for a physical device having physical components, the candidate phrases including noun phrases; generating a set of candidate concepts based on the extracted noun phrases; providing for a user to generate mapped concepts for physical components of the physical device by selecting, for each concept to be mapped, one of the physical components shown in a graphical representation of the physical device and at least one of the candidate concepts which is to be linked to that physical component, providing for a user to generate mapped concepts for actions associated with the physical components by selecting, for each concept to be mapped, an action shown in a graphical representation of the physical device and at least one of the candidate concepts for an action which is to be linked to that action, which are then stored in a mapped concept database, and storing the user-generated mapped concepts; and indexing the knowledge base based on the stored mapped concepts for physical components, whereby at least some of textual expressions in the knowledge base are linked to a respective physical component through one of the mapped concepts.