Helena Rasiowa and Cecylia Rauszer Research on Logical Foundations of Computer Science

There has been a long tradition of the interest of logicians in computer science and of computer scientists in logic. On the one hand, many problems raised and investigated by logicians before the emergence of computer science turned out to be relevant for the new science. We may quote here the notion of algorithm , model theory or relational systems. On the other hand, some problems stemming from computer science proved to be inspiring for logic, like algorithm complexity, vagueness of notions, etc. Besides "pure" logic, Professor Helena Rasiowa was deeply interested in computer science and its applications. She held the conviction that computer science can be of great signiicance in the development of modern logic because of the entirely new problems it brings forth and due to inspirations leading to new research areas. She was also fully aware of the signiicance of logic for computer science, and particularly of the theoretical foundations of logic. This point of view was not shared by all the logicians, even if some eminent representatives of the eld, like Dana Scott, were of the same opinion on the links between logic and computer science. It seems worthwhile to dwell upon this question a little more before turning to Rasiowa's papers relating logic and computer science. For simplicity, we shall focus our attention on the work of Polish logicians which had its impact on computer science even before this latter discipline came into being. This should provide a background for a clearer understanding of the achievements of Helena Rasiowa in this respect. The so-called parenthesis-free notation of Jan Lukasiewicz L29], L70] introduced in the twenties of our century was at rst considered a harmless curiosity.