1. A motivation for algebraic approaches to logics To realize the importance of the research work of Helena Rasiowa and Cecylia Rauszer in the area of algebraic methods in logics let us recall Got-tfried Wilhelm Leibniz. In [3] he wrote “Things are like numbers”. By this he meant that statements about complex things can be derived from statements about their simpler constituents by a process of combination analogous to arithmetic calculation on numbers. An algebraic calculation itself should be done by a machine. Thus he proposed: “It is unworthy of excellent [persons] to lose hours like slaves in the labor of calculation which could be safely relegated to anyone else if machines were used ” [7]. Having this in mind, he invented a device kn...