This resulted in non-zero counts for only 5 of the 162 instances in the development set (3.09%), and 35 of the 790 instances in the test set (4.43%).
these patterns fail to cover a vast majority of closest-antonyms, and even if the system guesses at random for all other instances, it attains only a modest improvement over the baseline (see row a, under "Related work," in Table 10).