This text grew out of lecture notes writtenl by Martin Weese of Humboldt
Universitat, Berlin, Germany in 1992/93. Winfried Just used part of these notes
during the same academic year in a lecture course on set theory for first and second
year graduate students at Ohio University, Athens, Ohio. While doing this, the
idea of writing up an English text of the lecture crossed his mind. The idea proved
irresistible enough to result in this book.
The genesis of this text accounts for some departures from the traditional textbook
format. Generally speaking, this is not so much a textbook that could form
the backbone of a lecture, but rather the text of the lecture itself. Accordingly,
our language is perhaps closer to spoken, colloquial English than to the standard
style of mathematical writing. Frequently, the text takes on the form of a dialogue
between the authors and the reader. The exercises form an integral part of this
dialogue and are not relegated to the end of sections.