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

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

A Geometric Proof of Calibration

G. STOLTZ, S. Mannor

Mathematics of Operations Research

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

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Mots clés : 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 Model of Financial Market Liquidity Based on Intermediary Capital


Journal of the European Economic Association

avril-mai 2010, vol. 8, n°2-3, pp.456-466

Départements : Finance, GREGHEC (CNRS)

A Note on the Evaluation of Information in Zero-Sum Repeated Games


Journal of Mathematical Economics

juillet 2010, vol. 46, n°4, pp. 393–399

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Mots clés : Repeated games, Zero-sum games, Value-of-information

Two players play a zero-sum repeated game with incomplete information. Before the game starts one player receives a private signal that depends on the realized state of nature. The rules that govern the choice of the signal are determined by the information structure of the game. Different information structures induce different values. The value-of-information function of a game associates every information structure with the value it induces. We characterize those functions that are value-of-information functions for some zero-sum repeated game with incomplete information

A Pattern-Based Approach to Protocol Mediation for Web Service Composition


Information and Software Technology

2010, vol. 52, n°3, pp.304-323

Départements : Informations Systems and Operations Management, GREGHEC (CNRS)

Acquisition Values and Optimal Financial (In)Flexibility

U. HEGE, C. Hennessy

Review of Financial Studies

juillet 2010, vol. 23, n°7, pp.2865-2899

Départements : Finance, GREGHEC (CNRS)

This article analyzes optimal financial contracts for an incumbent and potential entrant accounting for prospective asset mergers. Exercising a first-mover advantage, the incumbent increases his share of surplus by issuing public debt that appreciates in the event of merger. Incumbent debt reduces the equilibrium value of entrant assets and thus reduces the return to (likelihood of) entry through two channels: venture capitalists recover less in default and ownership rights provide weaker managerial incentives. High incumbent leverage has a countervailing cost, since the resulting debt overhang prevents ex post efficient mergers if merger surplus is low. Event risk covenants limiting counterparty debt are optimal for the incumbent, further limiting the entrant's share of merger surplus. A poison-put covenant is also optimal for the incumbent, allowing him to extract the same surplus with lower debt face value.

Agrégation séquentielle de prédicteursméthodologie générale et applications à la prévision de la qualité de lair et à celle de la consommation électrique


Journal de la Société Française de Statistique

2010, vol. 151, n°2, pp.66-106

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Mots clés : Sequential aggregation of predictors, Prediction with expert advice, Individual sequences, Air-quality forecasting, Prediction of electricity consumption

This paper is an extended written version of the talk I delivered at the "XLe Journées de Statistique" in Ottawa, 2004, when being awarded the Marie-Jeanne Laurent-Duhamel prize. It is devoted to surveying some fundamental as well as some more recent results in the field of sequential prediction of individual sequences with expert advice. It then performs two empirical studies following the stated general methodology: the first one to air-quality forecasting and the second one to the prediction of electricity consumption. Most results mentioned in the paper are based on joint works with Yannig Goude (EDF R&D) and Vivien Mallet (INRIA), together with some students whom we co-supervised for their M.Sc. theses: Marie Devaine, Sébastien Gerchinovitz and Boris Mauricette

An additively separable representation in the Savage framework


Journal of Economic Theory

septembre 2010, vol. 145, n°5, pp.2044-2054

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

accepté le 22/04/2010 (scopus)This paper proposes necessary and sufficient conditions for an additively separable representation of preferences in the Savage framework (where the objects of choice are acts: measurable functions from an infinite set of states to a potentially finite set of consequences). A preference relation over acts is represented by the integral over the subset of the product of the state space and the consequence space which corresponds to the act, where this integral is calculated with respect to an evaluation measure on this space. The result requires neither Savage's P3 (monotonicity) nor his P4 (weak comparative probability). Nevertheless, the representation it provides is as useful as Savage's for many economic applications. © 2010 Elsevier Inc. All rights reserved.Author Keywords Additive representation; Expected utility; Monotonicity; State-dependent utility

An Interpretive Account of Logical Aggregation Theory

P. MONGIN, F. Dietrich

Revue d'Economie Politique

novembre-décembre 2010, vol. 120, n°6, pp.929-972

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Abstract: Judgment aggregation theory, or rather, as we conceive of it here, logical aggregation theory generalizes social choice theory by having the aggregation rule bear on judgments of all kinds whatever, and not barely judgments of preference. It derives from Kornhauser and Sager's doctrinal paradox and Pettit's discursive dilemma, two problems that we restate by emphasizing their conceptual differences. Henceforth, we follow the main technical advances of the theory, from the first impossibility theorem proved by List and Pettit to the completely general results of Dietrich and Mongin. We stress the collective achievement of the canonical theorem - by Dietrich and List, Dokow and Holzman, Nehring and Puppe - which provided the theory with a specific method of analysis: it consists in mathematically characterizing the impossibility agendas of a given aggregator - i.e., the sets of propositions such that no collective judgment function exists with a certain list of axiomatic properties. The presentation is unified here by the use of formal logic, for which we claim relevance at every step, and by the above-mentioned distinction between the doctrinal paradox and the discursive dilemma, which we reelaborate upon technically.Author Keywords: Judgment Aggregation; Logical Aggregattion; Doctrinal Paradox; Discursive Dilemma; General Logic; Premiss-Based vs Conclusion; Based Approach; Social Choice TheoryKeyWords Plus: JUDGMENT AGGREGATION; ARROWS THEOREM; COLLEGIAL COURTS; IMPOSSIBILITY; PROPOSITIONS; CONSTRAINTS; LANGUAGE; AGENDAS; CHOICE; BELIEF

Analyzing the Performance of Data Loading and Processing in Relational Databases

I. Lungu, V. Diaconita, A. Bara, C. PARASCHIV

Journal of Economic Computation and Economic Cybernetics Studies and Research

2010, vol. 3, pp.109-122

Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Abstract. In this paper we are analyzing the performance of XML processing in different scenarios involving receiving large quantity of such documents. We are analyzing the loading and processing speed in four different scenarios involving an adapter written in an universal programming language and a relational database.Keywords: multi-thread; XML; integration; distributed systems