Litak, TadeuszPattinson, DirkSano, KatsuhikoSchroder, Lutz2015-12-13July 9-139783642315848http://hdl.handle.net/1885/82805We propose a generalization of first-order logic originating in a neglected work by C.C. Chang: a natural and generic correspondence language for any types of structures which can be recast as Set-coalgebras. We discuss axiomatization and completeness resKeywords: Axiomatization and completeness; Expressive power; First order logic; Model-theoretic; Predicate logic; Relational structures; Semantic characterizations; Topological spaces; Formal logic; Semantics; Automata theory201210.1007/978-3-642-31585-5-292016-02-24