1. A method for linking textual and physical concepts, comprising: extracting candidate phrases from a knowledge base for a device, 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 device by selecting, for each concept to be mapped, a physical component shown in a graphical representation of the device and at least one of the candidate concepts which is to be linked to that physical component; and indexing the knowledge base based on the mapped concepts, whereby at least some of textual expressions in the knowledge base are linked to a respective physical component through one of the mapped concepts.