Following previous work (Kwiatkowski et al., 2010), we make use of a higher-order unification learning scheme that defines a space of CCG grammars consistent with the (sentence, logical form) training pairs.
a traditional CCG grammar includes a lexicon Λ with entries like the following: where each lexical item w X : h has words w, a syntactic category X, and a logical form h. For the first example, these are "flights," N, and λ x. f light(x).