A Logical Form Parser for Correction and Consistency Checking of LF resources

In this paper we present ongoing work for the correction of Extended WordNet (XWN), the most extended freely downloadable resource of Logical Forms (LFs) – by the Human Language Technology Research Institute (HLTRI) of University of Texas at Dallas (UTD). In a previous paper we reported on type and number of errors detected in the 140,000 entries of the resource, which amounted to some 30%. This didn’t include problems related to inconsistencies from disconnected variables which were not computable at the time. We now created an LF parser that parses each entry after appropriate transformations. The parser has been created to count the number of disconnected variables, be they object variables or predicate event variables: the result is 56% of LFs containing some disconnected variable. We devised two procedures for correction: one lexical and the other structural which eventually allowed a dramatic reduction: the final count is now 24%. Additional work has been carried out to improve the general consistency by manual intervention on "inconsistent" outputs signaled by the parser and has reduce the number of errors to a reasonable percentage for such a resource, that is less that 15%.