We show that the basic categorical concept of an s-algebra as derived from the theory of Segal’s Γ-sets provides a unified description of several constructions attempting to model an algebraic geometry over the absolute point. It merges, in particular, the approaches using monöıds, semirings and hyperrings as well as the development by means of monads and generalized rings in Arakelov geometry....

This essay links two strands of Robert O. Keohane’s work. After Hegemony and his essays in International Regimes and Cooperation Under Anarchy relied on microeconomic reasoning to place the international institutions, norms, rules and procedures that we know as regimes at the center of the study of international relations. With Stephen Krasner, Robert Axelrod and others, Keohane defined the fun...

We consider stable three-dimensional matchings of three genders (3GSM). Alkan [Alkan, A., 1988. Nonexistence of stable threesome matchings. Mathematical Social Sciences 16, 207–209] showed that not all instances of 3GSM allow stable matchings. Boros et al. [Boros, E., Gurvich, V., Jaslar, S., Krasner, D., 2004. Stable matchings in three-sided systems with cyclic preferences. Discrete Mathematic...