A semantical approach to equilibria and rationality

Game theoretic equilibria are mathematical expressions of rationality. Rational agents are used to model not only humans and their software representatives, but also organisms, populations, species and genes, interacting with each other and with the environment. Rational behaviors are achieved not only through conscious reasoning, but also through spontaneous stabilization at equilibrium points. Formal theories of rationality are usually guided by informal intuitions, which are acquired by observing some concrete economic, biological, or network processes. Treating such processes as instances of computation, we reconstruct and refine some basic notions of equilibrium and rationality from the some basic structures of computation. It is, of course, well known that equilibria arise as fixed points; the point is that semantics of computation of fixed points seems to be providing novel methods, algebraic and coalgebraic, for reasoning about them.Comment: 18 pages; Proceedings of CALCO 200

Contract Enforcement, Social Efficiency, and Distribution: Some Experimental Evidence

We use economic experiments to investigate how different contract enforcement regimes affect efficiency and the distribution of surplus in a vertically coordinated market with buyer concentration. We find that if a third party (e.g., government) perfectly enforces contracts, social efficiency is enhanced. We also find that when third-party enforcement is imperfect, social efficiency will not necessarily decrease because trading partners find ways to self enforce contracts. However, opportunistic behavior by some traders leaves some sellers (growers) with ex post profits below reservation levels. Finally, partial or one-sided third-party enforcement causes significant efficiency losses by constraining subjects' ability to use informal enforcement instruments. Copyright 2007, Oxford University Press.

Enlargement processes and distributional conflicts: The politics of discriminatory membership in the European Union

This paper examines discriminatory membership in the European Union from a game-theoretical perspective. I argue that discriminatory membership enables the enlargement of international organizations with heterogenous member states. EU members impose discriminatory measures on new members to redistribute enlargement gains from new members to particularly negatively affected EU members as to render expansion pareto-efficient. The empirical findings of a probit analysis on the EU accession negotiations and outcomes of all five EU enlargement rounds support the theoretical claim. The EU grants acceding states restricted membership rights if distributional conflicts emerge. Moreover, the candidate’s bargaining power and the possibility of alternative compensation schemes influence the enlargement outcomes. Copyright Springer Science+Business Media, LLC 2007Enlargement, European Union, Discriminatory membership, Transitional periods,

An analysis of adverse selection, entrepreneurial activity, and the decision to go public

Asymmetric information, Entrepreneur, Initial public offering, Investment bank, Uncertainty, L26, R11, D81,

Market Conduct and Endogenous Lobbying: Evidence from the U.S. Mobile Telecommunications Industry

This paper empirically explores the relationship between firms' market behavior and their lobbying activities in a regulated market. In particular, we investigate whether the amount of contributions offered by cellular service providers to fund the campaigns of political parties affected market conduct in the early US mobile telecommunications industry. We structurally estimate market interactions while taking the potential endogeneity of lobbying decisions into account. Our results show that competition was more intense in those states where campaign contributions by the cellular industry have been higher. Furthermore, we reject the hypothesis that lobbying activities can be regarded as exogenous in the study of market conduct. Copyright Springer Science + Business Media, LLC 2007lobbying, campaign contributions, conjectural variations, mobile telecommunications, U.S., D72, L13, L51, L96, C31,

Dispersive effects from a comparison of electron and positron scattering from 12^{12}C

Dispersive effects have been investigated by comparing elastic scattering of electrons and positrons from $^{12}$C at the Saclay Linear Accelerator. The results demonstrate that dispersive effects at energies of 262 MeV and 450 MeV are less than $2\%$ below the first diffraction minimum $[0.95 < q_{eff} (fm^{–1}) < 1.66]$ in agreement with the prediction of Friar and Rosen. At the position of this minimum $(q_{eff} = 1.84 fm^{–1})$, the deviation between the positron scattering cross section and the cross section derived from the electron results is $–44\%\pm 30\%$

Impact of COVID-19 on Cardiovascular Testing in the United States Versus the Rest of the World

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-U.S. institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p &lt; 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection