7. The method of claim 1 , wherein: determining the subset of the solution nodes comprises: determining a highest solution node from among the solution nodes in the ending-character subtree, such that the score of the highest solution node is higher than any other of the scores of the solution nodes in the ending-character subtree.
7. The method of claim 1 , wherein: determining the subset of the solution nodes comprises: determining a highest solution node from among the solution nodes in the ending-character subtree, such that the score of the highest solution node is higher than any other of the scores of the solution nodes in the ending-character subtree. 8. The method of claim 7 , wherein: determining the highest solution node comprises: traversing the ending-character subtree from the ending-character query node to the highest solution node by repeatedly branching from a parent query node of the query nodes to a top child query node of the query nodes, wherein the subtree score of the top child query node is equal to the subtree score of the parent query node.