Valuation Theory

These are the revised notes of a course for graduate students and some seminar talks which I gave at the University of Rochester during Fall Term 1969/70. They would not have been written without the encouragement and the aid which I received, during all stages of the work, by friends from Rochester, Rio de Janeiro, and Bonn. I wish to thank all of them: Barbara Grabkowicz encouraged me to write these notes in English and read carefully parts of a preliminary manuscript, as did Gervasio G. Basto