The Saturnian Kilometric Radiation before the Cassini Grand Finale

The Saturnian Kilometric Radiation (SKR) is radiated from the auroral regions surrounding the kronian magnetic poles, above the ionosphere up to a few planetary radii. It directly compares to the auroral radio emissions emanating from other planetary magnetospheres such as the Earth and the giant planets. Our knowledge on SKR relied on remote observations of Voyager (flybys in 1980 and 1981) and Ulysses (distant observations in the 1990s) until Cassini started to orbit Saturn in 2004. Since then, it has been routinely observed from a large set of remote locations, but also in situ for the first time at a planet other than Earth. This article reviews the state of the art of SKR average remote properties, the first insights brought by in situ passes within its source region, together with some remaining questions before the Cassini Grand Finale and its close-in polar orbits.Comment: Refereed article; Proceedings of the 8th International Workshop on Planetary, Solar and Heliospheric Radio Emissions (PRE VIII), Seggauberg, Austria, Oct. 25-27, 201

Mechanism design with partially-specified participation games

This paper considers the implementation of an economic outcome under complete information when the strategic and informational details of the participation game are partially-specified. This means that full participation is required to be a subgame-perfect equilibrium for a large variety of extensive modifications of the simultaneous-move participation game in the same vein as Kalai [Large Robust Games, Econometrica 72 (2004) 1631-1665].mechanism design ; robust implementation ; strong Nash equilibrium ; partial subgame perfection ; collusion on participation

Identification and estimation of sequential English auctions

Brendstrup (2007) and Brendstrup and Paarsch (2006) claim that sequential English auction models with multi-unit demand can be identified from the distribution of the last stage winning price and without any assumption on bidding behavior in the earliest stages. We show that their identification strategy is not correct and that non-identification occurs even if equilibrium behavior is assumed in the earliest stages. For two-stage sequential auctions, an estimation procedure that has an equilibrium foundation and that uses the winning price at both stages is developed and supported by Monte Carlo experiments. Identification under general affiliated multi-unit demand schemes is also investigated.sequential auctions ; nonparametric identification ; nonparametric estimation

Ascending auctions: some impossibility results and their resolutions with final price discounts

When bidders are not substitutes, we show that there is no standard ascend-ing auction that implements a bidder-optimal competitive equilibrium under truthful bidding. Such an impossibility holds also in environments where the Vickrey payoff vector is a competitive equilibrium payoff and is thus stronger than de Vries, Schummer and Vohra s [On ascending Vickrey auctions for het-erogeneous objects, J. Econ. Theory, 132, 95-118] impossibility result with regards to the Vickrey payoff vector under general valuations. Similarly to Mishra and Parkes [Ascending price Vickrey auctions for general valuations, J. Econ. Theory, 132, 335-366], the impossibility can be circumvented by giving price discounts to the bidders from the final vector of prices. Nevertheless, the similarity is misleading: the solution we propose satisfies a minimality infor-mation revelation property that fails to be satisfied in any ascending auction that implements the Vickrey payoffs for general valuations. We investigate related issues when strictly positive increments have to be used under general continuous valuations.ascending auctions ; combinatorial auctions ; bidder-optimal competitive equilibrium ; non-linear pricing ; Vickrey payoffs ; increments

The econometrics of auctions with asymmetric anonymous bidders

We consider standard auction models when bidders' identities are not observed by the econometrician. First, we adapt the definition of identifiability to a framework with anonymous bids and we explore the extent to which anonymity reduces the possibility to identify private value auction models. Second, in the asymmetric independent private value model which is nonparametrically identified, we generalize Guerre, Perrigne and Vuong's estimation procedure [Optimal Nonparametric Estimation of First-Price Auctions, Econometrica 68 (2000) 525-574] and study the asymptotic properties of our multi-step kernel-based estimator. Third a test for symmetry is proposed. Monte Carlo simulations illustrate the practical relevance of our estimation and testing procedures for small data sets.auctions ; nonparametric identification ; nonparametric estimation ; tests for symmetry ; unobserved heterogeneity ; anonymous bids ; uniform convergence rate

"Upping the ante": How to design efficient auctions with entry?

In the symmetric independent private value model, we revisit auctions with entry by adding two additional ingredients: difficulties to commit to the announced mechanism, in particular not to update the reserve price after bidders took their entry decisions, and seller's ex ante uncertainty on her reservation value which calls for flexibility. Shill bidding or ex post rights to cancel the sale may provide some valuable flexibility in second price auctions. However, both fail to be efficient since the seller may keep the good while it would be efficient to allocate it to the highest bidder. The English auction with jump bids and cancelation rights is shown to implement the first best in large environments. On the positive side, special emphasis is put on the equilibrium analysis of auctions with shill bidding and on a variety of associated new insights including counterintuitive comparative statics and a comparison with posted-prices.auctions ; auctions with entry ; shill bidding ; commitment failure ; hold-up ; posted-price ; cancelation rights ; jump bids ; bilateral asymmetric information

Ascending auctions: some impossibility results and their resolutions with final price discounts

When bidders are not substitutes, we show that there is no standard ascend-ing auction that implements a bidder-optimal competitive equilibrium under truthful bidding. Such an impossibility holds also in environments where the Vickrey payoff vector is a competitive equilibrium payoff and is thus stronger than de Vries, Schummer and Vohra s [On ascending Vickrey auctions for het-erogeneous objects, J. Econ. Theory, 132, 95-118] impossibility result with regards to the Vickrey payoff vector under general valuations. Similarly to Mishra and Parkes [Ascending price Vickrey auctions for general valuations, J. Econ. Theory, 132, 335-366], the impossibility can be circumvented by giving price discounts to the bidders from the final vector of prices. Nevertheless, the similarity is misleading: the solution we propose satisfies a minimality infor-mation revelation property that fails to be satisfied in any ascending auction that implements the Vickrey payoffs for general valuations. We investigate related issues when strictly positive increments have to be used under general continuous valuations.Lorsque les enchérisseurs ne sont pas substituts, nous montrons qu'il n'existe pas de mécanisme d'enchères ascendantes qui implémente un équilibre concurrentiel qui soit optimal pour les enchérisseurs. Un tel résultat d'impossibilité reste vrai dans les environnements où les payements de Vickrey sont concurrentiels et est donc plus fort que le résultat d'impossibilité de De Vries, Schummer et Vohra [On ascending Vickrey auctions for heterogeneous objects, J. Econ. Theory, 132, 95-118] relatif à l'implémentation des payements de Vickrey sans restrictions sur les valuations. De la même manière que dans Mishra et Parkes [Ascending price Vickrey auctions for general valuations, J. Econ. Theory, 132, 335-366], l'impossibilité est levée si l'on autorise une phase de réduction des prix à la fin de l'enchère. La similarité est trompeuse : la solution que l'on propose satisfait une propriété de "minimalité" relativement à la révélation des préférences des enchérisseurs, une propriété qui ne peut être satisfaite dans aucune des enchères qui implémente les payements de Vickrey. Nous analysons aussi la robustesse de tels mécanismes à la présence d'incréments

Identification and estimation of sequential English auctions

Brendstrup (2007) and Brendstrup and Paarsch (2006) claim that sequential English auction models with multi-unit demand can be identified from the distribution of the last stage winning price and without any assumption on bidding behavior in the earliest stages. We show that their identification strategy is not correct and that non-identification occurs even if equilibrium behavior is assumed in the earliest stages. For two-stage sequential auctions, an estimation procedure that has an equilibrium foundation and that uses the winning price at both stages is developed and supported by Monte Carlo experiments. Identification under general affiliated multi-unit demand schemes is also investigated.Brendstrup (2007) et Brendstrup and Paarsch (2006) prétendent pouvoir identifier nonparamétriquement la fonction de distribution des préférences des enchérisseurs pour des enchères anglaises séquentielles avec demande multi-unitaire uniquement à partir de la distribution du prix à la dernière enchère. Nous montrons que la stratégie d'identification est inexacte et qu'il y a non-identification sans faire des hypothèses supplémentaires sur le comportement à l'équilibre. Pour les séquences avec deux enchères, une procédure d'estimation, utilisant les prix de deux enchères, est proposée. On étend la problématique à des modèles de demande multi-unitaire plus généraux

"Upping the ante": How to design efficient auctions with entry?

In the symmetric independent private value model, we revisit auctions with entry by adding two additional ingredients: difficulties to commit to the announced mechanism, in particular not to update the reserve price after bidders took their entry decisions, and seller's ex ante uncertainty on her reservation value which calls for flexibility. Shill bidding or ex post rights to cancel the sale may provide some valuable flexibility in second price auctions. However, both fail to be efficient since the seller may keep the good while it would be efficient to allocate it to the highest bidder. The English auction with jump bids and cancelation rights is shown to implement the first best in large environments. On the positive side, special emphasis is put on the equilibrium analysis of auctions with shill bidding and on a variety of associated new insights including counterintuitive comparative statics and a comparison with posted-prices.Dans le modèle symétrique à valeurs privées, nous revisitons les enchères avec entrée en ajoutant deux nouveaux ingrédients : les difficultés de s'engager sur le mécanisme annoncé, en particulier de s'engager sur le prix de réserve annoncé ex ante avant que les entrants potentiels n'aient pris leurs décisions et l'incertitude du vendeur sur sa valuation de réserve. Les enchères fantômes ou les droits d'annuler l'enchère peuvent apporter de la flexibilité. Cependant, ces comportements, souvent tolérés dans le monde des enchères, présentent des inconvénients et y sont associés de nouveaux insights contre-intuitifs par rapport à la théorie standard