Also , the Keller and Lapata ( 2003 ) approach will be undefined if the pair is unobserved on the web .
using the web to obtain frequencies for unseen bigrams
Frank Keller Mirella Lapata
The similarity-smoothed examples will be undefined if SIMS ( w ) is empty . Also , the Keller and Lapata ( 2003 ) approach will be undefined if the pair is unobserved on the web . As a reasonable default for these cases , we assign them a negative decision .
Also , the @@CITATION approach will be undefined if the pair is unobserved on the web .