"Fair Marriages:" An Impossibility

For the classical marriage model (introduced in Gale and Shapley, 1962) efficiency and envy-freeness are not always compatible, i.e., fair matchings do not always exist. However, for many allocation of indivisible goods models (see Velez, 2008, and references therein), fairness can be restored if a sufficiently large amount of money is available for distribution/compensation as well. Interpreting the agents as the objects to be allocated, one might try to restore fairness for marriage markets in a similar fashion. We prove that there are marriage markets where no amount of money can guarantee the existence of a fair allocation.efficiency, fairness, marriage markets, envy-freeness

Supercurrent and Local Coupling in the Wess-Zumino Model

We study the Wess-Zumino model with the coupling extended to a chiral superfield. In order to incorporate the renormalization effects a further external real field has to be introduced. It is then possible to derive a Callan-Symanzik equation and to prove renormalizability. By constructing the supercurrent in this context the whole machinery for describing the superconformal symmetries becomes available. The presence of the external fields allows also to define multiple insertions of all relevant composite operators. Interesting relations to the curved superspace treatment show up.Comment: 16 page

Stable Many-to-Many Matchings with Contracts

We consider several notions of setwise stability for many-to-many matching markets with contracts and provide an analysis of the relations between the resulting sets of stable allocations for general, substitutable, and strongly substitutable preferences. Apart from obtaining "set inclusion results" on all three domains, we introduce weak setwise stability as a new stability concept and prove that for substitutable preferences the set of pairwise stable matchings is nonempty and coincides with the set of weakly setwise stable matchings. For strongly substitutable preferences the set of pairwise stable matchings coincides with the set of setwise stable matchings.Many-to-Many Matching, Matching with Contracts, Pairwise Stability, Setwise Stability.

Consistency and Monotonicity in One-Sided Assignment Problems

One-sided assignment problems combine important features of two well-known matching models. First, as in roommate problems, any two agents can be matched and second, as in two-sided assignment problems, the payoffs of a matching can be divided between the agents. We take a similar approach to one-sided assignment problems as Sasaki (1995) for two-sided assignment problems and we analyze various desirable properties of solutions including consistency and weak pairwise-monotonicity. We show that for the class of solvable one-sided assignment problems (i.e., the subset of one-sided assignment problems with a non-empty core), if a subsolution of the core satisfies [indifference with respect to dummy agents, continuity, and consistency] or [Pareto indifference and consistency], then it coincides with the core (Theorems 1 and 2). However, we also prove that on the class of all one-sided assignment problems (solvable or not), no solution satisfies consistency and coincides with the core whenever the core is non-empty (Theorem 3). Finally, we comment on the difficulty in obtaining further positive results for the class of solvable one-sided assignment problems in line with Sasaki's (1995) characterizations of the core for two-sided assignment problems.(One-sided) assignment problems, consistency, core, matching.

Stability and Nash Implementation in Matching Markets with Couples

We consider two-sided matching markets with couples. First, we extend a result by Klaus and Klijn (2005, Theorem 3.3) and show that for any weakly responsive couples market there always exists a "double stable" matching, i.e., a matching that is stable for the couples market and for any associated singles market. Second, we show that for weakly responsive couples markets the associated stable correspondence is (Maskin) monotonic and Nash implementable. In contrast, the correspondence that assigns all double stable matchings is neither monotonic nor Nash implementable.Matching with Couples, (Maskin) Monotonicity, Nash Implementation, Stability, Weakly Responsive Preferences

Farsighted House Allocation

In this note we study von Neumann-Morgenstern farsightedly stable sets for Shapley and Scarf (1974) housing markets. Kawasaki (2008) shows that the set of competitive allocations coincides with the unique von Neumann-Morgenstern stable set based on a farsighted version of antisymmetric weak dominance (cf., Wako, 1999). We demonstrate that the set of competitive allocations also coincides with the unique von Neumann-Morgenstern stable set based on a farsighted version of strong dominance (cf., Roth and Postlewaite, 1977) if no individual is indifferent between his endowment and the endowment of someone else.housing markets, indivisible goods, farsightedness, von Neumann-Morgenstern stable sets, top trading cycles, competitive allocations

Farsighted Stability for Roommate Markets

Using a bi-choice graph technique (Klaus and Klijn, 2009), we show that a matching for a roommate market indirectly dominates another matching if and only if no blocking pair of the former is matched in the latter (Proposition 1). Using this characterization of indirect dominance, we investigate von Neumann-Morgenstern farsightedly stable sets. We show that a singleton is von Neumann-Morgenstern farsightedly stable if and only if the matching is stable (Theorem 1). We also present roommate markets with no and with a non-singleton von Neumann-Morgenstern farsightedly stable set (Examples 1 and 2).core, farsighted stability, one- and two-sided matching, roommate markets, von Neumann-Morgenstern stability.

Plädoyer für eine kulturorientierte Annäherung

Der Aufsatz setzt sich kritisch mit zentralen theoretischen Prämissen der aktuellen Journalismusforschung auseinander. In der Konzentration auf den nachrichtlichen Journalismus einerseits und die Kommunikatoren andererseits gelingt es der Journalistik nicht, aktuelle Veränderungen angemessen zu beschreiben und analytisch zu erfassen. Anstelle der Paradigmen „System“ versus „Individuum“ wird hier das Paradigma „Kultur“ als erkenntnisleitende Perspektivierung eingesetzt. Auf Basis der Cultural Studies können vor allem auch die populären Formen des Journalismus und seine Publikumsorientierung integrativ untersucht werden. Information und Unterhaltung werden dann nicht länger als funktionaler Gegensatz konstruiert. Zugleich gelingt es mit dem Kreislauf medialer Produktion und Rezeption, den gesellschaftlichen Prozess der Sinnvermittlung durch Journalismus transparent zu machen und damit Forschungsaufgaben für eine kulturorientierte Journalistik zu formulieren