Aris Filos-Ratsikas

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We study the problem of approximate social welfare maximization (without money) in onesided matching problems when agents have unrestricted cardinal preferences over a finite set of items. Random priority is a very well-known truthful-in-expectation mechanism for the problem. We prove that the approximation ratio of random priority is Θ(n) while no(More)
We study a mechanism design version of matching computation in graphs that models the game played by hospitals participating in pairwise kidney exchange programs. We present a new randomized matching mechanism for two agents which is truthful in expectation and has an approximation ratio of 3/2 to the maximum cardinality matching. This is an improvement(More)
The Fisher market model is one of the most fundamental resource allocation models in economics. In a Fisher market, the prices and allocations of goods are determined according to the preferences and budgets of buyers to clear the market. In a Fisher market game, however, buyers are strategic and report their preferences over goods; the marketclearing(More)
We study the envy-free pricing problem in linear multi-unit markets with budgets, where there is a seller who brings multiple units of a good, while several buyers bring monetary endowments. Our goal is to compute an envy-free (item) price and allocation, i.e. an outcome where all the demands of the buyers are met given their budget constraints, which(More)
The Adjusted Winner procedure is an important fair division mechanism proposed by Brams and Taylor for allocating goods between two parties. It has been used in practice for divorce settlements and analyzing political disputes. Assuming truthful declaration of the valuations, it computes an allocation that is envy-free, equitable and Pareto optimal. We show(More)
We study the truthful facility assignment problem, where a set of agents with private most-preferred points on a metric space are assigned to facilities that lie on the metric space, under capacity constraints on the facilities. The goal is to produce such an assignment that minimizes the social cost, i.e., the total distance between the most-preferred(More)
We study the Price of Anarchy of mechanisms for the well-known problem of one-sided matching, or house allocation, with respect to the social welfare objective. We consider both ordinal mechanisms, where agents submit preference lists over the items, and cardinal mechanisms, where agents may submit numerical values for the items being allocated. We present(More)
We consider the egalitarian welfare of random assignment mechanisms when agents have unrestricted cardinal utilities over the objects. We define and give bounds on how well different random assignment mechanisms approximate the optimal egalitarian value (OEV) and investigate the effect that different well-known properties like ordinality, envyfreeness, and(More)