Contributions of Arto Salomaa to Multiple-Valued Logic

In scientific community, especially among mathematicians and computer scientists, Arto Salomaa is renowned as a founder of Automata Theory and Formal Languages. It is however less widely known that Salomaa started his research work in the area of multiple-valued logic, where he received his PhD degree in 1960 from the University of Turku, Finland. In this way, research in multiple-valued logic provided foundations for later work of Professor Salomaa. The paper presents a short summary of the work of Arto Salomaa in multiple-valued logic.