1. An intrusion detection system for detecting and defeating an unauthorized intrusion within a computer network of an infrastructure element of a high value target, the system comprising: a pre-processor configured to receive data from the computer network of the infrastructure element of the high value target and to output filtered data; a grammar applicator configured to apply grammars produced using a grammar based compression and learning algorithm to the filtered data; a decision making device in communication with the grammar applicator and configured to provide a recommendation based on an input from the grammar applicator as to whether the data in the computer network constitutes the unauthorized intrusion; and an emulator in communication with the decision making device and configured to expand a sampling of the filtered data using a polymorphic transformation to allow the decision making device to further analyze the sampled data to determine the unauthorized intrusion.