Page 7 - Textos de Matemática Vol. 39

PREFACE
This collection of mathematical papers is dedicated to our colleague and friend Eduardo Marques de Sa´ on the occasion of his 60th birthday.
Throughout his professional life, Marques de Sa´ has fulfilled many roles, as a researcher of high calibre, as an outstanding teacher, as mentor of stu- dents at all levels (including six PhD students) and in many different areas, as a successful popularizer of Mathematics, as an active participant in Depart- ment life. Common traits can be detected in his activities: exacting standards, an absolute intellectual integrity, and an intense passion for Mathematics, all of Mathematics. If a subject attracts his attention, he will not leave it until understanding is complete. A problem will be abandoned only after the most thorough effort to solve it.
He has always taken his teaching very seriously. This can be gauged by a simple fact: there are few courses taught by Marques de Sa´ in the last 30 years for which he has not carefully prepared a set of notes for the students. For many years these were simply handwritten, but were even clearer than if they were typed. As he moved from course to course, many subjects were covered, from Analysis in several variables and Complex Analysis to Commutative Algebra and advanced Logic, with the texts running sometimes in the hundreds of pages. With characteristic modesty, he never thought of transforming these notes into formal books, although they were always highly polished and original. Some of them he may even have forgotten by now.
A similar detachment can be seen in his research. Of course he has pub- lished a number of papers, currently around 45 (one of them, written with three co-authors during a long visit to the USA, is possibly the most cited among papers by Portuguese mathematicians; another was the backbone of his PhD thesis, for which he was awarded the Householder Prize). But the actual study- ing and thinking about Mathematics, as well as helping others with their work, was and is always the most important thing to him. More than once he had to be pushed by colleagues to write up and submit his results to a journal.