However, finding the optimal subset of training instances is difficult, as there exist 2 N possible solutions for a relation type with N training instances.
this paper proposes an approximate training instance selection algorithm as follows: 1) Computing the centroid of ith relation type as 2) Finding the set of training instances which can most compactly span the centroid by solving: 3) Ranking all training instances according to their absolute coefficient weight value ; 4) Selecting top p percent ranked instances as final training instances.