A Contraction-free and Cut-free Sequent Calculus for Propositional Dynamic Logic

B. HILL, F. Poggiolesi

Studia Logica

2010, vol. 94, n°1, pp.1-26

Departments: Economics & Decision Sciences, GREGHEC (CNRS)

A Geometric Proof of Calibration

G. STOLTZ, S. Mannor

Mathematics of Operations Research

November 2010, vol. 35, n°4, pp.721-727

Departments: Economics & Decision Sciences, GREGHEC (CNRS)

Keywords: Calibration, Approachability, Convergence rates, Computational complexity

We provide yet another proof of the existence of calibrated forecasters; it has two merits. First, it is valid for an arbitrary finite number of outcomes. Second, it is short and simple and it follows from a direct application of Blackwell's approachability theorem to a carefully chosen vector-valued payoff function and convex target set. Our proof captures the essence of existing proofs based on approachability (e.g., the proof by Foster [Foster, D. 1999. A proof of calibration via Blackwell's approachability theorem. Games Econom. Behav. 29 73–78] in the case of binary outcomes) and highlights the intrinsic connection between approachability and calibration

A gestão estratégica dos hospitais na França: balanço e perspectivas


Ciência & Saúde Coletiva

August 2010, vol. 15, n°5, pp.2285-2296

Departments: Strategy & Business Policy

A longitudinal study of the influence of alliance network structure and composition on firm exploratory innovation


Academy of Management Journal

August 2010, vol. 53, n°4, pp.890-913

Departments: Strategy & Business Policy

This study examines the influence of the structure and composition of a firm's alliance network on its exploratory innovation--innovation embodying knowledge that is novel relative to the firm's extant knowledge. A longitudinal investigation of 77 telecommunications equipment manufacturers indicated that the technological diversity of a firm's alliance partners increases its exploratory innovation. Further, network density among a firm's alliance partners strengthens the influence of diversity. These results suggest the benefits of network "closure" (wherein a firm's partners are also partners) and access to diverse information can coexist in an alliance network and that these combined benefits increase exploratory innovation

A Model of Financial Market Liquidity Based on Intermediary Capital


Journal of the European Economic Association

April-May 2010, vol. 8, n°2-3, pp.456-466

Departments: Finance, GREGHEC (CNRS)

We present a model of financial market liquidity provided by financially constrained intermediaries. We show that market liquidity increases with the level of intermediary capital. We also characterize conditions under which intermediaries play a stabilizing or destabilizing role in markets. Finally, we sketch a number of areas, including welfare and public policy, on which the model can shed light.