Bergadano, FrancescoMatwin, StanMichalski, Ryszard S.Zhang, Jianping2006-11-142006-11-141991-05Bergadano, F., Matwin, S., Michalski, R. S. and Zhang, J., "Learning Two-tiered Descriptions of Flexible Concepts: The POSEIDON System," Reports of the Machine Learning and Inference Laboratory, MLI 91-3, School of Information Technology and Engineering, George Mason University, Fairfax, VA, May, 1991.https://hdl.handle.net/1920/16702900463 bytesapplication/pdfen-USLearning Two-tiered Descriptions of Flexible Concepts: The POSEIDON SystemTechnical report