Hysteresis in West German Unemployment Reconsidered

The view that high unemployment in West Germany and other European countries is caused by a path dependence effect - or "hysteresis" effect - is quite popular among economists. However, because of an identification problem, much of the empirical evidence for this hypothesis is not fu lly convincing. This paper suggests a testing procedure that overcomes this problem. It is argued that in a cointegration framework it is reasonable to define hysteresis as the absence of weak exogeneity of the explanatory variables. Building on a cointeg ration model of the employment rate in West Germany, I find only weak evidence for hysteresis.Cointegration, hysteresis, trade unions, unemployment

Regulation and Internet Access in Germany

We explain the recent events in the German market for online access using a model of a regulated monopoly renting phone lines to retailers. Retailers offer either a linear or a flat tariff to consumers. Consumer heterogeneity leads to adverse selectiion. We show why market entry for flatrate firms is difficult under a linear wholesale tariff. With both a linear and a flat wholesale tariff the consumer market shows a mixture of tariffs as well. When marginal costs are zero it is optimal to have a wholesale flatrate only. However, marginal moves towards this equilibrium are not always welfare improving.Internet, flatrate, adverse selection

Shaded Tangles for the Design and Verification of Quantum Programs (Extended Abstract)

We give a scheme for interpreting shaded tangles as quantum programs, with the property that isotopic tangles yield equivalent programs. We analyze many known quantum programs in this way -- including entanglement manipulation and error correction -- and in each case present a fully-topological formal verification, yielding in several cases substantial new insight into how the program works. We also use our methods to identify several new or generalized procedures.Comment: In Proceedings QPL 2017, arXiv:1802.0973

A classical groupoid model for quantum networks

We give a mathematical analysis of a new type of classical computer network architecture, intended as a model of a new technology that has recently been proposed in industry. Our approach is based on groubits, generalizations of classical bits based on groupoids. This network architecture allows the direct execution of a number of protocols that are usually associated with quantum networks, including teleportation, dense coding and secure key distribution

Apportionment, Fiscal Equalization and Decentralized Tax Enforcement

We study tax evasion and decentralized tax enforcement in a federal economy with mobile capital and the endogenous formation of multiregional companies. Regions use their enforcement policy as a strategic instrument to engage in fiscal competition. Within this framework, we analyze the uncoordinated policy choice under formula apportionment (FA) and compare it to the incentives which derive from fiscal equalization (FE). As both systems redistribute collected revenues but not enforcement costs, they distort the regions' incentives to enforce taxes. At the same time, jurisdictions partially internalize the fiscal externalities caused by their enforcement policy. We show that the tradeoff between these two opposing effects differs between FA and FE, and crucially depends on the degree of interregional firm integration under FA. We discuss conditions under which FA, FE or a joint system of FA cum FE provides the ‘best’ incentives for decentralized tax enforcement.Tax Enforcement, Tax Evasion, Formula Apportionment, Fiscal Equalization, Tax Revenue Sharing