1. A method for recognizing cause-effect relations in natural language documents to generate a cause-effect knowledge base comprising: providing text from at least one natural language document; recognizing one or more expanded Subject-Action-Object (eSAO) sets in the text, wherein each eSAO set has one or more eSAO components; matching the one or more eSAO sets against cause-effect relationship patterns; generating one or more eSAO cause-effect relations based on the matching, wherein the eSAO cause-effect relation comprises a cause eSAO and an effect eSAO; and storing the one or more eSAO cause-effect relations in a knowledge base.