Although we could classify and use all the nouns that appeared in the training data (with an adjective which is different from the given one), we do not adopt such an alternative, because it will incorporate even non-collocating pairs such as "green+idea" into seeds, resulting in possible degradation of classification performance.
we sample unseen pairs consisting of a seen noun and a seen adjective from a corpus, classify the pairs with the latent variable model, and add them to the seed set.