On the evolutionary edge of altruism: a game-theoretic proof of Hamilton’s rule for a simple case of siblings

We offer a game-theoretic proof of Hamiltons rule for the spread of altruism. For a simple case of siblings, we show that the rule can be derived as the outcome of a one-shot prisoners dilemma game between siblings.JEL Classification: A13, C70, D64Correspondence to: Oded Stark, ZEF, University of Bonn, Walter-Flex-Strasse 3, 53113 Bonn, GermanyWe are indebted to an anonymous referee and to Uwe Cantner for helpful comments and suggestions. Partial financial support from the National Institute on Aging (grant RO1-AG13037) and from the Humboldt Foundation is gratefully acknowledged.     

Diffusion and Innovation of New Technologies under Skill Heterogeneity

This article presents a model of innovation and diffusion of machines which embody a new technology. Users of the machines are heterogenous in their skill level. Skilled machine-users adopt new machines first, while unskilled users wait until machines become more user-friendly and reliable. The improvement of machines is the engine of diffusion, and it is carried out by the monopolist machine producer. The speed of diffusion is affected by the skill distribution in the economy. At any point in time, the machine producer can innovate a new generation of machines. The timing of innovation is also influenced by the skill distribution.     

On strategic complementarity conditions in Bertrand oligopoly

Summary. For Bertrand duopoly with linear costs, we establish via a single (counter-)example that: (i) A new monotone transformation of the firms' profit functions may lead to the supermodularity of transformed profits when the standard log and identity transformations both fail to do so, and (ii) Topkis's notion of critical sufficient condition for monotonicity of a Bertrand firm's best-reply correspondence cannot be extended to rely only on positive unit costs. Received: January 16, 2001; revised version: March 20, 2002 RID="*" ID="*" This work was completed while the first author was visiting the Institute for Industrial Economics at the University of Copenhagen during Spring 2000. Their financial support and stimulating research environment are gratefully acknowledged. The views expressed here are those of the authors and should not be attributed to the European Commission. Correspondence to: R. Amir     

Existence of a competitive equilibrium in a one sector growth model with heterogeneous agents and irreversible investment

Summary. We prove existence of a competitive equilibrium in a version of a Ramsey (one sector) model in which agents are heterogeneous and gross investment is constrained to be non negative. We do so by converting the infinite-dimensional fixed point problem stated in terms of prices and commodities into a finite-dimensional Negishi problem involving individual weights in a social value function. This method allows us to obtain detailed results concerning the properties of competitive equilibria. Because of the simplicity of the techniques utilized our approach is amenable to be adapted by practitioners in analogous problems often studied in macroeconomics. Received: September 13, 2001; revised version: December 9, 2002 RID="*" ID="*" We are grateful to Tapan Mitra for pointing out errors as well as making very valuable suggestions. Thanks are due to Raouf Boucekkine and Jorge Duran for additional helpful discussions. We also thank an anonymous referee for his/her helpful comments. The second author acknowledges the financial support of the Belgian Ministry of Scientific Research (Grant ARC 99/04-235 “Growth and incentive design”) and of the Belgian Federal Goverment (Grant PAI P5/10, “Equilibrium theory and optimization for public policy and industry regulation”). Correspondence to: C. Le Van     

Change vs. decline: A comparative analysis of the evolution of TFP in Italian regions,with a particular attention to the case of Turin

Recently a debate emerged in Italy, about the changing pattern of specialization in the sectors traditionally considered as cornerstones of the national economy. Such changes are far from representing a hopeless process of decline. Rather this process should be regarded as a step in a process of structural change, in which one can find the ingredients of creative destruction. This leads to spell out the hypothesis that the Italian economy has been taking a new direction, rather than a dead-end. In this paper we carry out an analysis of the evolution of Total Factor Productivity in the different macro-sectors at the regional level, over the period 1982-2001. The results of the analysis confirm the existence of a generalized process of transition characterized by the growing weight of service sectors. Within the Piedmont region, the case of Turin is of paramount importance, as it has influenced the national economy since the early decades of the 20^th century. (JEL: O41, O47)     

Private R&;D and Spillovers in European Agriculture

The objective of this paper is to present econometric evidence of the effects of economic incentives, public policies, and institutions on national aggregate private agricultural R&D investments. The main hypothesis we will test in this paper is whether agricultural R&D spillovers represent a disincentive for national private R&D. More specifically, we will test if the spillovers function, which is a determinant of private R&D, follows a quadratic form and if private R&D is determined by the role of incentives and institutions.A previous draft of this paper was presented at the 57th International Atlantic Economic Conference, Lisbon, Portugal, 10–14 March 2004. Comments from participants have been very useful to improve the paper.