The paper is a theoretical study of a generalization of the le xicographic rule for combining ordering relations. We define the concept of priority operato r: a priority operator maps a family of… (More)

We study algebras whose elements are relations, and the operations are natural \manipulations" of relations. This area goes back to 140 years ago to works of De Morgan, Peirce, Schrr oder (who… (More)

We study relativity theory as a theory in the sense of mathematical logic. We use first-order logic (FOL) as a framework to do so. We aim at an “analysis of the logical structure of relativity… (More)

Languages and families of binary relations are standard interpretations of Kleene algebras. It is known that the equational theories of these interpretations coincide and that the free Kleene algebra… (More)

We study algebras whose elements are relations, and the operations are natural \manipulations" of relations. This area goes back to 140 years ago to works of De Morgan, Peirce, Schrr oder (who… (More)

Using a combinatorial theorem of Herwig on extending partial isomorphisms of relational structures, we give a simple proof that certain classes of algebras, including Crs, polyadic Crs, and WA, have… (More)