PREFACE Whatthisbookisabout.Thetheoryofsetsisavibrant,excitingmathematical theory,withitsownbasicnotions,fundamentalresultsanddeepopenprob- lems,andwithsignificantapplicationstoothermathematicaltheories.Atthe sametime,axiomaticsettheoryisoftenviewedasafoundationofmathemati