To strike a better balance between having a rich representation of the context surrounding a spatial relation and improving the learner's ability to generalize, we extract a subtree from a parse tree and use it as the value of the structured feature.
given relation candidate triplet (e 1 ,e 2 ,e 3 ), where spatial elements e 1 , e 2 , and e 3 are posited in roles r 1 , r 2 , and r 3 , respectively, and the associated syntactic parse tree T , we extract our parse subtree from T as follows.