I am retiring from Case Western Reserve University. Future postal mail should be sent to Charles Wells 105 South Cedar Street Oberlin, OH 44074, USA and you should use only the email address and phone number below. The University has not yet told me whether they will allow me to keep my webpage at the address below, but the odds are that they will. Charles Wells, Oberlin, Ohio, USA. EMAIL: charles@freude.com. HOME PHONE: 440 774 1926. PROFESSIONAL WEBSITE: http://www.cwru.edu/artsci/math/wells/home.html PERSONAL WEBSITE: http://www.oberlin.net/~cwells/index.html