A tribute to Mario Petrich

Abstract

has had a great influence on semigroup theory and on several generations of semigroup theorists. His extensive and deep contributions to the theory of regular, in particular, completely regular and inverse semigroups, and to a great variety of other subjects, earned him a special place in the history of our relatively young area. He is appreciated and admired by many of the people who have got the chance to know him and have benefitted from his insight and ideas.Mario Petrich was born in 1932 in Split, at that time in Yugoslavia. He spent part of his childhood and adolescence there under Italian rule, during World War II. Then Split was recovered by Yugoslavia, and he lived there until he was 20 years old, completing three years of studies in mathematics at the University of Zagreb. Then he left Yugoslavia, first went to West Germany and then to the USA. There he first worked as a messenger boy in New York at $1 per hour for 7 months, and then continued his studies. He completed his M.Sc. at Midwest University, and took his Ph.D. at the University of Washington, Seattle in 1961. After working at various institutions for shorter terms, partly in applied mathematics, he took a position at Pennsylvania State University in 1964. In 1976 he left the United States for personal reasons. He became a 'citizen of the world', accepting limited term appointments. Over the years, he was hosted, as a visiting professor or such, by many universities in various countries where he engaged in many successful collaborations: in