The ability to recognize objects and their relationships is at the core of intelligent behavior. This, in turn, depend on one’s ability of perceiving similarity or dissimilarity between objects, be physical or abstract ones. Hence, if we are interested to make computers behave with any degree of intelligence, we have to write programs that can work with relevant representation of objects and means to compute their similarities or lack thereof, i.e., dissimilarity (obviously, they are two faces of the same coin).
The white paper: Measuring Similarity between Objects