I am indebted to Rakesh Agrawal of the IBM Almaden Research Laboratory for introducing me to data mining in conversation and through his papers. I also had useful discussions with Ted Selker, Joe Halpern, Jeff Ullman, Nimrod Megiddo, Rajeev Motwani, Brad Efron, Christos Papadimitriou, Ron Fagin, Tom Costello, and Gregory Tseytin.
This work was partly supported by ARPA (ONR) grant N00014-94-1-0775 and partly by IBM while I was visiting faculty during the summer of 1996 and since.