For example, in the field of natural language processing (NLP) the similarity among features is quite intuitive. Features such as words, "n"-grams, or syntactic "n"-grams can be quite similar, though formally they are considered as different features in the VSM. For example, words “play” and “game” are different words and thus mapped to different points in VSM; yet they are semantically related. In case of "n"-grams or syntactic "n"-grams, Levenshtein distance can be applied (in fact, Levenshtein distance can be applied to words as well).