1. In a data processing system, a method of generating an object recognition system for recognizing goal objects, each comprised of one or more input entities, the method performed by the data processing system comprising: defining input entity recognition objects relative to input entities; defining goal recognition objects relative to input entities through recognition object trees, each having input entity recognition objects as leaves and a goal object at its root; and generating from plural recognition object trees a decision tree of an object recognition system for recognizing goal objects from the input entities, the decision tree being separate from the recognition object trees and comprising decision nodes testing for recognition objects and comprising goal objects, from plural recognition object trees, at leaves of the decision tree, the step of generating the decision tree comprising, beginning at the root of the decision tree, recursively selecting, for the nodes of the decision tree, recognition objects from the recognition trees beginning from the leaves of the recognition trees, and grouping recognition trees to define branches from the nodes of the decision tree based on whether the recognition trees include the selected recognition objects.