1. A method for improving natural language processing conducted by a natural language model, the method comprising: accessing, at a first node in a logical hierarchy configured to guide classification of a plurality of documents by the natural language model, at least one rule associated with the first node, said at least one rule defining a first factor for determining whether a document among the plurality of documents is to be classified into the first node; identifying a percolation criterion associated with a second node in the logical hierarchy that is a parent node to the first node, said percolation criterion indicating that the at least one rule associated with the first node is to be associated also with the second node; based on the identified percolation criterion, associating the at least one rule with the second node such that the at least one rule defines a second factor for determining whether the document is to also be classified into the second node; accessing the document for natural language processing; and classifying the document according to the logical hierarchy by determining whether the document is to be classified into at least one of the second node and the first node based on the at least one rule associated with both the first node and the second node.