@misc{42299, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Eine ökonomische Analyse der Piraterie in zweiseitigen Softwaremärkten}}}, year = {{2020}}, } @misc{42304, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Kulturelle Unterschiede beim Lösen von Verhandlungsproblemen}}}, year = {{2020}}, } @misc{42298, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Productivity optimization through project matching}}}, year = {{2020}}, } @misc{42306, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Matching Mechanisms and Organ Exchange}}}, year = {{2020}}, } @misc{42300, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Cartel Fines in the European Union}}}, year = {{2020}}, } @misc{42302, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Anspruchsregeln in Verhandlungen}}}, year = {{2020}}, } @misc{42292, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Die Zusammenstellung eines Sortiments als Beispiel interdependenter Verhandlungen}}}, year = {{2020}}, } @misc{42294, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Matching in Netzwerken}}}, year = {{2020}}, } @article{1139, abstract = {{We investigate the degree of price competition among telecommunication firms. Underlying a Bertrand model of price competition, we empirically model pricing behaviour in an oligopoly. We analyse panel data of individual pricing information of mobile phone contracts offered between 2011 and 2017. We provide empirical evidence that price differences as well as reputational effects serve as a signal to buyers and significantly affect market demand. Additionally, we find that brands lead to an increase in demand and thus are able to generate spillover effects even after price increase.}}, author = {{Kaimann, Daniel and Hoyer, Britta}}, journal = {{Applied Economics Letters}}, number = {{1}}, pages = {{54--57}}, publisher = {{Taylor and Francis Online}}, title = {{{Price competition and the Bertrand model: The paradox of the German mobile discount market}}}, doi = {{10.1080/13504851.2018.1436141}}, volume = {{26}}, year = {{2019}}, } @article{2256, abstract = {{Social psychology studies the "common enemy effect", the phenomenon that members of a group work together when they face an opponent, although they otherwise have little in common. An interesting scenario is the formation of an information network where group members individually sponsor costly links. Suppose that ceteris paribus, an outsider appears who aims to disrupt the information flow within the network by deleting some of the links. The question is how the group responds to this common enemy. We address this question for the homogeneous connections model of strategic network formation, with two-way flow of information and without information decay. For sufficiently low linkage costs, the external threat can lead to a more connected network, a positive common enemy effect. For very high but not prohibitively high linkage costs, the equilibrium network can be minimally connected and efficient in the absence of the external threat whereas it is always empty and ineffi cient in the presence of the external threat, a negative common enemy effect. For intermediate linkage costs, both connected networks and the empty network are Nash for certain cost ranges.}}, author = {{Hoyer, Britta and Haller, Hans}}, journal = {{Journal of Economic Behavior & Organization}}, pages = {{146--163}}, title = {{{The Common Enemy Effect under Strategic Network Formation and Disruption}}}, doi = {{10.1016/j.jebo.2019.03.011}}, volume = {{162}}, year = {{2019}}, } @article{80, abstract = {{Models on network formation have often been extended to include the potential of network disruption in recent years. Whereas the theoretical research on network formation under the threat of disruption has thus gained prominence, hardly any experimental research exists so far. In this paper, we therefore experimentally study the emergence of networks including the aspect of a known external threat by relating theoretical predictions by Dzuibiński and Goyal (2013) to actual observed behaviour. We deal with the question if subjects in the role of a strategic Designer are able to form safe networks for least costs while facing a strategic Adversary who is going to attack their networks. Varying the costs for protecting nodes, we designed and tested two treatments with different predictions for the equilibrium network and investigated whether one of the least cost equilibrium networks was more likely to be reached. Furthermore, the influence of the subjects’ farsightedness on their decision-making process was elicited and analysed. We find that while subjects are able to build safe networks in both treatments, equilibrium networks are only built in one of the two treatments. In the other treatment, predominantly safe networks are built but they are not for least costs. Additionally, we find that farsightedness –as measured in our experiment– has no influence on whether subjects are able to build safe or least cost equilibrium networks. Two robustness settings with a reduced external threat or more liberties to modify the initial networks qualitatively confirm our results. Overall, in this experiment observed behaviour is only partially in line with the theoretical predictions by Dzuibiński and Goyal (2013).}}, author = {{Endres, Angelika Elfriede and Recker, Sonja and Mir Djawadi, Behnud and Hoyer, Britta}}, journal = {{Journal of Economic Behavior and Organization }}, pages = {{708--734}}, title = {{{Network Formation and Disruption - An Experiment: Are equilibrium networks too complex?}}}, doi = {{10.1016/j.jebo.2018.11.004}}, volume = {{157}}, year = {{2019}}, } @phdthesis{8080, abstract = {{This thesis investigates approximate pure Nash equilibria in different game-theoretic models. In such an outcome, no player can improve her objective by more than a given factor through a deviation to another strategy. In the first part, we investigate two variants of Congestion Games in which the existence of pure Nash equilibria is guaranteed through a potential function argument. However, the computation of such equilibria might be hard. We construct and analyze approximation algorithms that enable the computation of states with low approximation factors in polynomial time. To show their guarantees we use sub games among players, bound the potential function values of arbitrary states and exploit a connection between Shapley and proportional cost shares. Furthermore, we apply and analyze sampling techniques for the computation of approximate Shapley values in different settings. In the second part, we concentrate on the existence of approximate pure Nash equilibria in games in which no pure Nash equilibria exist in general. In the model of Coevolving Opinion Formation Games, we bound the approximation guarantees for natural states nearly independent of the specific definition of the players' neighborhoods by applying a concept of virtual costs. For the special case of only one influential neighbor, we even show lower approximation factors for a natural strategy. Then, we investigate a two-sided Facility Location Game among facilities and clients on a line with an objective function consisting of distance and load. We show tight bounds on the approximation factor for settings with three facilities and infinitely many clients. For the general scenario with an arbitrary number of facilities, we bound the approximation factor for two promising candidates, namely facilities that are uniformly distributed and which are paired.}}, author = {{Feldotto, Matthias}}, title = {{{Approximate Pure Nash Equilibria in Congestion, Opinion Formation and Facility Location Games}}}, doi = {{10.17619/UNIPB/1-588}}, year = {{2019}}, } @techreport{7630, abstract = {{In this paper, we analyze a credence goods model adjusted to the health care market with regulated prices and heterogeneous experts. Experts are physicians and are assumed to differ in their cost of treating a small problem. We investigate the effects of this heterogeneity on the physicians’ level of fraud and on the patients’ search for second opinions. We find that introducing a fraction of more efficient low-cost physicians always increases social welfare, but in some cases only because of the raised physicians’ surplus. When the low-cost physicians’ cost advantage is small, imposing a share of low-cost physicians does not change the equilibrium fraud level. When the cost advantage is large, however, different changes in the fraud level occur depending on the share of generated low-cost physicians, the search rate and the initial level of fraud.}}, author = {{Heinzel, Joachim Maria Josef}}, keywords = {{credence goods, treatment efficiency, heterogeneous experts, overcharging}}, publisher = {{CIE Working Paper Series}}, title = {{{Credence Goods Markets with Heterogeneous Experts}}}, volume = {{118}}, year = {{2019}}, } @techreport{8873, abstract = {{We analyze a credence goods market adapted to a health care market with regulated prices, where physicians are heterogeneous regarding their fairness concerns. The opportunistic physicians only consider monetary incentives while the fair physicians, in addition to a monetary payoff, gain an non-monetary utility from being honest towards patients. We investigate how this heterogeneity affects the physicians’ equilibrium level of overcharging and the patients’ search for second opinions (which determines overall welfare). The impact of the heterogeneity on the fraud level is ambiguous and depends on several factors such as the size of the fairness utility, the share of fair physicians, the search level and the initial fraud level. Introducing heterogeneity does not affect the fraud or the search level when the share of fair physicians is small. However, when social welfare is not at its maximum, social welfare always increases if we introduce a sufficiently large share of fair physicians.}}, author = {{Heinzel, Joachim Maria Josef}}, keywords = {{credence goods, heterogeneous experts, fairness, overcharging}}, publisher = {{CIE Working Paper Series}}, title = {{{Credence Goods Markets with Fair and Opportunistic Experts}}}, volume = {{119}}, year = {{2019}}, } @inproceedings{5471, abstract = {{We characterise the set of dominant strategy incentive compatible (DSIC), strongly budget balanced (SBB), and ex-post individually rational (IR) mechanisms for the multi-unit bilateral trade setting. In such a setting there is a single buyer and a single seller who holds a finite number k of identical items. The mechanism has to decide how many units of the item are transferred from the seller to the buyer and how much money is transferred from the buyer to the seller. We consider two classes of valuation functions for the buyer and seller: Valuations that are increasing in the number of units in possession, and the more specific class of valuations that are increasing and submodular. Furthermore, we present some approximation results about the performance of certain such mechanisms, in terms of social welfare: For increasing submodular valuation functions, we show the existence of a deterministic 2-approximation mechanism and a randomised e/(1-e) approximation mechanism, matching the best known bounds for the single-item setting.}}, author = {{Lazos, Philip and Goldberg, Paul and Skopalik, Alexander and Gerstgrasser, Matthias and de Keijzer, Bart}}, booktitle = {{Proceedings of the Thirty-Third AAAI Conference on Artificial Intelligence (AAAI)}}, location = {{Honolulu, Hawaii, USA}}, title = {{{ Multi-unit Bilateral Trade}}}, doi = {{10.1609/aaai.v33i01.33011973}}, year = {{2019}}, } @techreport{15202, abstract = {{In this paper, we analyze the two-dimensional Nash bargaining solution (NBS) deploying a standard labor market negotiations model (see McDonald and Solow, 1981; Creedy and McDonald, 1991). We show that the two-dimensional bargaining problem can be decomposed into two one-dimensional problems such that the (Cartesian) product of the solutions of these problems replicates the solution of the two-dimensional problem, if the NBS is applied. However, this decomposition fails for any solution concept that does not satisfy the axiom of Independence of Irrelevant Alternatives (IIA axiom). Our decomposition result has significant implications for actual negotiations, as it allows for the decomposition of a multi-issue bargaining problem into a set of simpler problems, in particular a set of single-issue bargaining problems. In this way, the decomposition may help facilitate negotiations in labor markets and also in other environments.}}, author = {{Haake, Claus-Jochen and Upmann, Thorsten and Duman, Papatya}}, keywords = {{Labor market negotiations, Efficient bargains, Nash bargaining solution, Sequential bargaining, Restricted bargaining games}}, publisher = {{CIE Working Paper Series, Paderborn University}}, title = {{{The Decomposability of the Nash Bargaining Solution in Labor Markets}}}, volume = {{128}}, year = {{2019}}, } @techreport{15204, abstract = {{We criticize some conceptual weaknesses in the recent literature on coalitional TUgames and propose, based on our critics, a new definition of dual TU-games that coincides with the one in the literature on the class of super-additive games. We justify our new definition in four alternative ways: 1. Via an adequate definition of ecient payo vectors. 2. Via a modification of the Bondareva-Shapley duality. 3. Via an explicit consideration of \coalition building". 4. Via associating general TU-games to coalition-production economies. Rather than imputations, we base our analysis on a modification of aspirations.}}, author = {{Aslan, Fatma and Duman, Papatya and Trockel, Walter}}, keywords = {{TU-games, duality, core, c-Core, cohesive games, complete game efficiency}}, publisher = {{CIE Working Paper Series, Paderborn University}}, title = {{{Duality for General TU-games Redefined}}}, volume = {{121}}, year = {{2019}}, } @article{13148, abstract = {{This paper examines the evolutionary stability of behaviour in contests where players’ participation can be stochastic. We find, for exogenously given participation probabilities, players exert more effort under the concept of a finite-population evolutionarily stable strategy (FPESS) than under Nash equilibrium (NE). We show that there is ex-ante overdissipation under FPESS for sufficiently large participation probabilities, if, and only if, the impact function is convex. With costly endogenous entry, players enter the contest with a higher probability and exert more effort under FPESS than under NE. Importantly, under endogenous entry, overdissipation can occur for all (Tullock) contest success functions, in particular those with concave impact functions.}}, author = {{Gu, Yiquan and Hehenkamp, Burkhard and Leininger, Wolfgang}}, issn = {{0167-2681}}, journal = {{Journal of Economic Behavior & Organization}}, pages = {{469--485}}, title = {{{Evolutionary equilibrium in contests with stochastic participation: Entry, effort and overdissipation}}}, doi = {{10.1016/j.jebo.2019.06.011}}, year = {{2019}}, } @inproceedings{10281, abstract = {{Competing firms tend to select similar locations for their stores. This phenomenon, called the principle of minimum differentiation, was captured by Hotelling with a landmark model of spatial competition but is still the object of an ongoing scientific debate. Although consistently observed in practice, many more realistic variants of Hotelling's model fail to support minimum differentiation or do not have pure equilibria at all. In particular, it was recently proven for a generalized model which incorporates negative network externalities and which contains Hotelling's model and classical selfish load balancing as special cases, that the unique equilibria do not adhere to minimum differentiation. Furthermore, it was shown that for a significant parameter range pure equilibria do not exist. We derive a sharp contrast to these previous results by investigating Hotelling's model with negative network externalities from an entirely new angle: approximate pure subgame perfect equilibria. This approach allows us to prove analytically and via agent-based simulations that approximate equilibria having good approximation guarantees and that adhere to minimum differentiation exist for the full parameter range of the model. Moreover, we show that the obtained approximate equilibria have high social welfare.}}, author = {{Feldotto, Matthias and Lenzner, Pascal and Molitor, Louise and Skopalik, Alexander}}, booktitle = {{Proceedings of the 18th International Conference on Autonomous Agents and MultiAgent Systems}}, location = {{Montreal QC, Canada}}, pages = {{1949----1951}}, publisher = {{International Foundation for Autonomous Agents and Multiagent Systems}}, title = {{{ From Hotelling to Load Balancing: Approximation and the Principle of Minimum Differentiation}}}, year = {{2019}}, } @techreport{10332, abstract = {{We analyze the incentives for retail bundling and the welfare effects of retail bundling in a decentralized distribution channel with two retailers and two monopolistic manufacturers. One manufacturer exclusively sells his good to one retailer, whereas the other manufacturer sells his good to both retailers. Thus, one retailer is a monopolist for one product but competes with the other retailer in the second product market. The two-product retailer has the option to bundle his goods or to sell them separately. We find that bundling aggravates the double marginalization problem for the bundling retailer. Nevertheless, when the retailers compete in prices, bundling can be more profitable than separate selling for the retailer as bundling softens the retail competition. The ultimate outcome depends on the manufacturers’ marginal costs. Given retail quantity competition, however, bundling is in no case the retailer’s best strategy. Furthermore, we show that profitable bundling reduces consumer and producer surplus in the equilibrium.}}, author = {{Heinzel, Joachim Maria Josef}}, keywords = {{retail bundling, leverage theory, double marginalization}}, publisher = {{CIE Working Paper Series}}, title = {{{Bundling in a Distribution Channel with Retail Competition}}}, year = {{2019}}, }