... documents and find that the fea-ture vectors corresponding to some of these docu-ments (particularly the short ones) have all zeroes in them. In other words, none of the bigrams from the training set ... available.612Finally, previous work has also investigated fea-tures that do not fall into any of the above cate-gories. For instance, instead of representing the polarity of a term using a binary value, ... Proceedings of the COLING/ACL 2006 Main Conference Poster Sessions, pages 611–618,Sydney, July 2006.c2006 Association for Computational LinguisticsExamining the Role of Linguistic Knowledge...