A.A. 2007/2008

6 Dicembre 2007 - Prof. Ignacio Garcia-Jurado (Universidade de Santiago de Compostela)
Transfers, Contracts and Strategic Games
Abstract
This talk analyses the role of transfer payments and strategic contracting within two-person strategic form games with monetary payoffs. First, it introduces the notion of transfer equilibrium as a strategy combination for which individual stability can be supported by allowing the possibility of transfers of the induced payoffs. Clearly, Nash equilibria are transfer equilibria, but under common regularity conditions the reverse is also true. This result typically does not hold for finite games without the possibility of randomisation, and transfer equilibria for this particular class are studied in some detail.
The second part of the talk introduces, also within the setting of finite games, contracting on monetary transfers as an explicit strategic option, resulting in an associated two-stage contract game. In the first stage of the contract game each player has the option of proposing transfer schemes for an arbitrary collection of outcomes. Only if the players fully agree on the entire set of transfer proposals, the payoffs of the game to be played in the second stage are modified accordingly.
The main results provide explicit characterisations of the sets of payoff vectors that are supported by Nash equilibrium and virtual subgame perfect equilibrium, respectively.
The seminar is based on a joint work with J. Kleppe, R. Hendrickx, P. Borm and G. Fiestras-Janeiro
Presentazione

6 Dicembre 2007 - Prof. Fioravante Patrone (Università di Genova)
Nobel a Hurwicz, Maskin e Myerson: cos'è il "mechanism design"?
Abstract
Verrà messo in evidenza quale sia il problema che affronta il "mechanism design", sia mediante considerazioni generali che attraverso qualche esempio specifico.
Un classico campo di applicazione è dato dalle aste. Avendo a disposizione diversi tipi di aste (che sarebbero, in questo contesto, i meccanismi), si tratta di scegliere quella più opportuna per ottenere un qualche determinato risultato. Ad esempio, per ottenere il massimo profitto atteso, se si tratta della vendita di un oggetto.
Sarà sottolineata la connessione con la teoria dei giochi ed, in particolare, con i giochi ad informazione incompleta.

3 Marzo 2008 - Dott. Silvia Villa (Università di Genova)
Scambi di donatori dal punto di vista della teoria dei giochi
Abstract
In questo seminario descriverò un metodo per aumentare le possibilità di ricevere un trapianto basato sull'organizzazione di scambi di donatori tra coppie incompatibili.
Questo sistema presenta diverse caratteristiche, che verranno analizzate dal punto di vista della teoria dei giochi.
Particolare attenzione verrà riservata alla proprietà di “incentive compatibility”, che è direttamente collegata all'uso di strategie che prevedano che i giocatori coinvolti rivelino sinceramente l'informazione privata in loro possesso.
Presentazione

11 Marzo 2008 - Dott. Simona Sanguineti (Università di Genova)
Introduzione alla logistica economica
Abstract
Nel seminario sarà innanzitutto illustrato il concetto di logistica in generale e le sue principali funzioni, per poi focalizzarsi sulla parte più economica dell'argomento ed in particolare il ruolo che i trasporti vi ricoprono.
Presentazione

14 Aprile 2008 - Prof. Anna Khmelnitskaya (St. Petersburg Institute for Economics and Mathematics, Russian Academy of Sciences)
Values for graph-restricted games with coalition structure
Abstract
We consider a new model of TU games endowed with both coalition and cooperation structures. It is assumed that cooperation (via bilateral agreements between participants) is only possible either among the entire coalitions of the coalition structure, in other terms a priori unions, or among single players within a priori unions, no communication and therefore no cooperation is allowed between single players from distinct elements of the coalition structure. This approach allows to model different network situations, in particular, telecommunication problems, distribution of goods among different cities (countries) along highway networks connecting the cities and local road networks within the cities, or sharing an international river with multiple users but without international firms, i.e., when no cooperation is possible among single users from different levels along the river, and so on. A cooperation structure is introduced by means of graphs of two types, first, presenting links among the a priori unions of the coalition structure and second, presenting links among players within each a priori union. We consider cooperation structures presented by combinations of graphs of different types - general undirected graphs, cycle-free graphs, line-graphs with linearly ordered players.
Our main approach to the value is close to that of both Myerson (1977) and Aumann and Drèze (1974): it is based on ideas of component efficiency and one or another deletion link property, and it treats an a priori union as a self-contained unit. Moreover, to link both communication levels between and within a priori unions we incorporate the idea of the quotient game property of the Owen value (1977) as well.
We introduce the new values axiomatically and show that they possess the explicit formula representation that in many cases leads to quite simple computational algorithms. We investigate the stability and the distribution of the Harsanyi dividends. We show that the problem of sharing a river among multiple users without international firms can be embedded into the framework of the introduced model.
Presentazione