For ease of exposition, we will illustrate the problem using a special case of the SS framework where the sentences are concept definitions in a dictionary such as WordNet (Fellbaum, 1998) (WN).
the sentence corresponding to the concept definition of bank#n#1 is a sparse vector in X containing the following observed words where X ij = 0: the 0.1, f inancial 5.5, institution 4, that 0.2, accept 2.1, deposit 3, and 0.1, channel 6, the 0.1, money 5, into 0.3, lend 3.5, activity 3 All the other words (girl, car,..., check, loan, business,...) in matrix X that do not occur in the concept definition are considered missing words for the concept entry bank#n#1, thereby their X ij = 0 .