 Furthermore, cylindric algebras, essentially Boolean algebras equipped with unary cylindric operations \(C_x\) which are intended to capture the existential quantifiers (\(\exists x\)), were introduced in the years 1948–1952 by Tarski, working with his students Louise Chin and Frederick Thompson (see Henkin &amp; Tarski 1961), to create an algebra of logic that captured the expressive power of the first-order theory of binary relations. Polyadic algebra is another approach to an algebra of logic for first-order logic—it was created by Halmos (1956c). The focus of work in these systems was again to see to what extent one could parallel the famous results of Stone for Boolean algebra from the 1930s.