Dedicated to my sons, Randall, Jeffrey, and Thomas

Copyright © 2000 by H. Jerome Keisler.

This work is licensed under the Creative CommonsAttribution-NonCommercial-ShareAlike License.To view a copy of this licence, visithttp://creativecommons.org/licenses/by-nc-sa/2.0/or send a letter to Creative Commons, 559 NathanAbbott Way, Stanford, California, 93405, USA.

Revised September 2007