Der Perlentaucher unter den Buchläden Eichendorff21

**Steven Givant** is a Professor of Mathematics and Computer Science at Mills College, California. As a long-term collaborator of Alfred Tarski-one of the great logicians-Givant has been involved first-hand in the development of the field of relation algebras since the 1970s. His other books include _Introduction to Relation Algebras_ and _Advanced Topics in Relation Algebras_ (Springer, 2017), _Duality Theories for Boolean Algebras with Operators_ (Springer, 2014), _Introduction to Boolean Algebras_ , with Paul Halmos (Springer, 2009), _Logic as Algebra_ , with Paul Halmos (MAA, 1998), __ and _A Formalization of Set Theory without Variables_ , with Alfred Tarski (AMS, 1987). He was also a coeditor, with Ralph McKenzie, of the collected papers of Alfred Tarski (Birkhäuser, 1986). **Hajnal Andréka** is a Professor of Mathematics at the Alfréd Rényi Institute of Mathematics in the Hungarian Academy of Sciences. She has been a prominent figure in the development of relation algebra theory since the 1970s and won the prestigious Alfréd Rényi Prize in 1987. Her other books include _Universal Algebraic Logic_ , with István Németi and Ildikó Sain (Birkhäuser, 2017), _Decision Problems for Equational Theories of Relation Algebras_ , with Steven Givant and István Németi (AMS, 1997), and _Cylindric Set Algebras_ , with Leon Henkin, J. Donald Monk, Alfred Tarski, and István Németi (Springer, 1981).