OPUS - Volltextserver Universität Passau
Not a member yet
1021 research outputs found
Sort by
Generalized Nash equilibrium problems with mixed-integer variables
No full textWe consider generalized Nash equilibrium problems (GNEPs) with non-convex strategy spaces and non-convex cost functions. This general class of games includes the important case of games with mixed-integer variables for which only a few results are known in the literature. We present a new approach to characterize equilibria via a convexification technique using the Nikaido–Isoda function. To any given instance of the GNEP, we construct a set of convexified instances and show that a feasible strategy profile is an equilibrium for the original instance if and only if it is an equilibrium for any convexified instance and the convexified cost functions coincide with the initial ones. We develop this convexification approach along three dimensions: We first show that for quasi-linear models, where a convexified instance exists in which for fixed strategies of the opponent players, the cost function of every player is linear and the respective strategy space is polyhedral, the convexification reduces the GNEP to a standard (non-linear) optimization problem. Secondly, we derive two complete characterizations of those GNEPs for which the convexification leads to a jointly constrained or a jointly convex GNEP, respectively. These characterizations require new concepts related to the interplay of the convex hull operator applied to restricted subsets of feasible strategies and may be interesting on their own. Note that this characterization is also computationally relevant as jointly convex GNEPs have been extensively studied in the literature. Finally, we demonstrate the applicability of our results by presenting a numerical study regarding the computation of equilibria for three classes of GNEPs related to integral network flows and discrete market equilibria
Sharing is caring? The effect of negative peer-to-peer experiences on loyalty intentions in the sharing economy
No full textNegative experiences with other users (i.e., negative peer-to-peer [P2P] experiences), are a highly prevalent problem of sharing economy business models with potentially negative consequences for the platform. This paper investigates the effect of negative P2P experiences on users’ platform loyalty intentions. Based on trust transfer theory, we test a moderated serial mediation suggesting that negative P2P experiences negatively affect platform loyalty intentions via a decrease in peer trust and a subsequent decrease in platform trust. The results of an online scenario-experiment (n = 265) and an online survey (n = 237) in the home-sharing context support this notion by showing a negative peers-to-platform trust transfer effect. In addition, we identified the type of negative experience (outcome-related vs. process-related) and prior relationship satisfaction as contingency factors. This paper draws platform providers’ attention to the potential threat stemming from negative experiences between users and provide advice on how to attenuate a negative spillover-effect on the platform
A probabilistic approach to Lorentz balls l(^n)(q,1)
No full textWe develop a probabilistic approach to study the volumetric and geometric properties of unit balls |B(^n)(q,1) of finite-dimensional Lorentz sequence spaces l(^n)(q,1). More precisely, we show that the empirical distribution of a random vector X^(n) uniformly distributed on its volume normalized unit ball converges weakly to a compactly supported symmetric probability distribution with explicitly given density; as a consequence we obtain a weak Poincaré-Maxwell-Borel principle for any fixed number k in |N of coordinates of X^(n) as n grows infinitly. Moreover, we prove a central limit theorem for the largest coordinate of X^(n), demonstrating a quite different behavior than in the case of the l(^n)(q) balls, where a Gumbel distribution appears in the limit. Finally, we prove a Schechtman-Schmuckenschläger type result for the asymptotic volume of intersections of volume normalized l(^n)(q,1) and l(^n)(p) balls
A simple model of buyer–seller networks in international trade
No full textThe recent literature on firm-to-firm trade has documented salient empirical regularities of the buyer–seller network. We show that surprisingly many of these regularities emerge by superimposing the stochastic balls-and-bins structure of Armenter and Koren (2014) to firms in a classical Krugman (1980) model. Our approach amounts to a re-interpretation of Krugman (1980) and relies on randomized bundling of Krugman-varieties into heterogeneous firms, economically neutral ‘sales units’ that import foreign varieties but belong to local firms, and a statistical reporting threshold that applies to firm-to-firm transactions. We argue that our model provides an important benchmark for the assessment of theoretical models that aim to identify the determinants of firm-to-firm networks
Navigating crises: Gold's role as a safe haven for U.S. sectors
No full textThis paper investigates the correlation between U.S. sectors and gold, and whether gold can serve as a safe haven for investors in specific U.S. sectors during the global financial crisis, COVID-19, and the Russia-Ukraine war. We use data from the Standard & Poor's Depository Receipts (SPDR) Select Sector Exchange Traded Fund (ETF) to capture the performance of the respective sectors. Our findings document that gold is a weak safe haven for most U.S. sectors. Gold is not a safe investment for energy, materials, utilities, and consumer staples. Gold does provide vital protection for financial, consumer discretionary, industrial, technology, and healthcare
When weather wounds workers : the impact of temperature on workplace accidents
No full textWe study the effects of temperature on occupational health using administrative data on Swiss occupational accidents from 1996 to 2019. Our results imply that on hot days (T ≥ 30 ◦C) the number of occupational accidents increases by 7.4% and on ice days (T < 0 ◦C) by 6.3%, relative to mild days. We find that extreme temperatures cause an average of 2600 workplace accidents each year, costing CHF 91 million annually. We provide suggestive evidence for insufficient sleep on hot days as a mechanism. While extreme temperatures worsen occupational health, we observe limited labor supply adaption for most workers
Can social media encourage diabetes self-screenings? A randomized controlled trial with Indonesian Facebook users
No full textNudging individuals without obvious symptoms of non-communicable diseases (NCDs) to undergo a health screening remains a challenge, especially in middle-income countries, where NCD awareness is low but the incidence is high. We assess whether an awareness campaign implemented on Facebook can encourage individuals in Indonesia to undergo an online diabetes self-screening. We use Facebook’s advertisement function to randomly distribute graphical ads related to the risk and consequences of diabetes. Depending on their risk score, participants receive a recommendation to undergo a professional screening. We were able to reach almost 300,000 individuals in only three weeks. More than 1400 individuals completed the screening, inducing costs of about US9
Re-embeddings of affine algebras via Gröbner fans of linear ideals
No full textGiven an affine algebra R=K[x1,⋯,xn]/Iover a field K , where I is an ideal in the polynomial ring P=K[x1,⋯,xn], we examine the task of effectively calculating re-embeddings of I , i.e., of presentations R=P′/I′such that P′=K[y1,⋯,ym]has fewer indeterminates. For cases when the number of indeterminates n is large and Gröbner basis computations are infeasible, we have introduced the method of Z -separating re-embeddings in Kreuzer et al. (J Algebra Appl 21, 2022) and Kreuzer, et al. (São Paulo J Math Sci, 2022). This method tries to detect polynomials of a special shape in I which allow us to eliminate the indeterminates in the tuple Z by a simple substitution process. Here we improve this approach by showing that suitable candidate tuples Z can be found using the Gröbner fan of the linear part of I . Then we describe a method to compute the Gröbner fan of a linear ideal, and we improve this computation in the case of binomial linear ideals using a cotangent equivalence relation. Finally, we apply the improved technique in the case of the defining ideals of border basis schemes
Ehrlich, Gianna Luisa; Der konsumentenbasierte Markenwert von Nachrichtenmedien : Muster der Genese und Wirkung von starken Medienmarken.
No full textMore effective pandemic management through social science policy advice? A comment on the article by Jörn Knobloch in issue 4/2023
No full textDer Kommentar setzt sich kritisch mit Jörn Knoblochs Analyse des Corona-Pandemiemanagements in Deutschland auseinander. Er hinterfragt die Behauptung Knoblochs, durch eine stärkere Berücksichtigung von Sozialwissenschaftlern in den einschlägigen Beratungsgremien hätte eine effektivere Krisenbewältigung erreicht werden können. Der Beitrag fokussiert zum einen die strukturellen epistemischen Grenzen sowohl der biomedizinischen Wissenschaften als auch der empirischen Sozialforschung. Zum anderen beleuchtet er die Eigenlogik politischer Entscheidungsprozesse, die durch die Notwendigkeit der Unsicherheitsabsorption und Systemstabilisierung geprägt sind und gegenüber externen Einflüssen als relativ immun erscheinen. Der Beitrag plädiert für eine differenzierte Betrachtung der Schnittstelle zwischen wissenschaftlicher Beratung und politischer Praxis und mahnt eine kritische Reflexion der Rolle und der Grenzen der wissenschaftsgestützten Politikberatung an.The comment critically examines Jörn Knobloch’s analysis of the COVID-19 pandemic management in Germany. It questions Knobloch’s claim that a more effective crisis management could have been achieved by giving greater consideration to social scientists in the relevant advisory committees. The reply focuses on the structural epistemic limits of both biomedical sciences and empirical social research. Furthermore, it highlights the inherent logic of political decision-making processes, which are characterized by the need for uncertainty absorption and system stabilization, and appear relatively immune to external influences. The contribution calls for a nuanced consideration of the interface between scientific advice and political practice, and urges a critical reflection on the role and limits of science-based policy advice