by crus754 | Sep 15, 2010
Speaker: Motty Perry
Affiliation: Hebrew University of Jerusalem and University of Warwick
Title: Dynamic Optimal Contracts with Adverse Selection and Moral Hazard
Date: Wednesday, 15 September 2010
Time: 4pm
Location: 301-242 [Science Centre, Symonds Street]
Abstract: This paper studies a novel dynamic principle – agent setting with moral hazard and adverse selection (persistent as well as repeated). In the model an expert whose skills is his private information, faces a finite sequence of tasks, one after the other. Each task’s level of difficulty is an independent random variable revealed, upon arrival, to the expert only. On each task in turn the expert choose whether to pass or to work, and how much effort to exert. While the choice of work/pass is public, his effort is his private information.
The optimal contract-pair which takes advantage of the dynamic nature of the interaction is characterized. It is shown that as the length of the contract increases, the expected transfer per-period goes down and in the limit approaches the optimal payment when agent’s skills are publicly known.
One example of such a dynamic interaction is the one occurs between a money manager who receives funds from investors, and then observes a sequence of investment opportunities. Another example that nicely fits this model is the design of optimal contracts to surgeons of different quality, to treat a flow of patients whose problems are the surgeon’s private information.
Joint work with A. Gershkov.
by crus754 | Jul 1, 2009
Speaker: Tatyana Gvozdeva
Affiliation: The University of Auckland
Title: A new bound for simple games
Date: Monday, 13 Jul 2009
Time: 3:00 pm
Location: Room 401
Comparative probability orders are closely related to simple games and cancellation conditions for these orders are very similar to trading transforms for games. In this talk we exploit this similarity to obtain new examples of simple games using Fishburn’s examples of comparative probability orders. These examples give us a new lower bound on the lengths of certificate of non-weightedness for simple games, which is better than the best known one given by Taylor and Zwicker (1992). Our lower bound is linear in the number of players while the one by Taylor and Zwicker is equal to the square root of n.
by crus754 | Jun 16, 2009
Speaker: Matthew Ryan
Affiliation: Economics Department, The University of Auckland
Title: Mixture Sets – An Introduction
Date: Monday, 22 Jun 2009
Time: 3:00 pm
Location: Room 401, Science Centre
A mixture set is an abstract convex structure introduced by Herstein and Milnor (Econometrica, 1953) as a foundation for the expected utility representation theorem (representation of preferernces by a linear utility function). Mixture sets combine a set X with a ternary relation T that maps (x,y,t) to an element of X for each x,y in X and each t in [0,1] — the t-mixture of x and y. Herstein and Milnor consider infinite mixture sets, but the notion is well-defined even for finite X. This raises the question of the relationship between mixture sets and abstract convex geometries (discussed by Arkadii in previous Workshops). It appears that neither is a special case of the other. This talk will introduce mixture sets, and what is — and isn’t — known about them.
by crus754 | May 12, 2009
Speaker: Tatyana Gvozdeva
Affiliation: The Univesity of Auckland
Title: Roughly weighted simple games
Date: Monday, 18 May 2009
Time: 3:00 pm
Location: Room 401
In this talk we will give a necessary and sufficient condition for a simple game to have rough weights. As in the classical Taylor-Zwicker (1992) theorem this will be done in terms of trading transforms. We will give some bounds on the lengths of certificates of non-existence of rough weights and explore games with small number of players.
by crus754 | May 5, 2009
Speaker: Arkadii Slinko
Affiliation: The University of Auckland
Title: Simple games: what are the questions?
Date: Monday, 11 May 2009
Time: 3:00 pm
Location: Room 401
A simple game consists of a finite set of objects (players) and some subsets (coalitions) are marked as winning and the rest are therefore losing. The monotonicity condition is imposed which says that a superset of a winning coalition is winning. Simple games are used to model the distribution of power in a body of agents, say which coalitions of countries can pass a motion in the UN Security Council. A simple game also may model the access structure of a secret-sharing scheme – in this case winning coalitions are those who authorised to know the secret.
In this talk I will introduce some basic concepts and formulate a number of open questions. Most are concerned either with finding conditions under which the power of a player can be expressed by a real number or conditions under which all players can be ranked in accordance to their power.
The concept of a trading transform will be introduced and several numerical functions which characterise the game will be introduced too. The emphasis will be on games that have extremal values of those parameters. Gabelman games will be considered in particular.
The talk will not present anything new. A week later Tatyana Gvozdeva will discuss some new results.
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