93 citations · 245 across the 42 of their papers we have counts for
58 papers
Computational Aspects of Distortion
Soroush Ebadian, Aris Filos-Ratsikas, Mohamad Latifian +1
The distortion framework in social choice theory allows quantifying the efficiency of (randomized) selection of an alternative based on the preferences of a set of agents. We make…
The Delegation Dilemma: Economies of Scale, Accountability, and Polycentric Governance
Arin Mukhopadhyay, Aris Filos-Ratsikas, Panayiotis Danassis
Many collective-action systems are neither fully decentralized nor fully centralized: agents voluntarily organize into institutions that share organizational costs and delegate dec…
Binary -Center under a Hard Threshold with Applications to Delegated Voting
Jakub Dargaj, Aris Filos-Ratsikas, Paul W. Goldberg
We study the problem of covering binary strings of the same length, possibly with missing entries, by a fixed number of center strings, such that each input string is within a give…
Nash Equilibria in Auctions with Pacing Strategies: Complexity and Inefficiency
Aris Filos-Ratsikas, Charalampos Kokkalis, Mohamad Latifian
We introduce and study Auctions with Pacing Strategies (APS) games, a full-information model in which utility-maximizing bidders compete across many simultaneous first-price auctio…
Approximate Envy-Free Allocations up to any Goods
Aris Filos-Ratsikas, Georgios Kalantzis, Fangxiao Wang
We study the problem of finding approximate envy-free allocations up to any goods (-EFkX), when agents have additive values over goods in a bundle. As our main result, we sh…
Proportionality Degree in Participatory Budgeting
Aris Filos-Ratsikas, Sreedurga Gogulapati, Georgios Kalantzis
We initiate the study of the proportionality degree for participatory budgeting, with a particular focus on two popular methods: the Method of Equal Shares (MES) and Phragmen's Seq…
Efficient Equilibrium Computation in Symmetric First-Price Auctions
Aris Filos-Ratsikas, Yiannis Giannakopoulos, Alexandros Hollender +1
We study the complexity of computing Bayes-Nash equilibria in single-item first-price auctions. We present the first efficient algorithms for the problem, when the bidders' values…
A Theoretical Approach to Stablecoin Design via Price Windows
Katherine Molinet, Aris Filos-Ratsikas
In this paper, we explore the short- and long-term stability of backed stablecoins offering constant mint and redeem prices to all agents. We refer to such designs as price window-…
The Distortion of Stable Matching
Aris Filos-Ratsikas, Georgios Kalantzis
We initiate the study of distortion in stable matching. Concretely, we aim to design algorithms that have limited access to the agents' cardinal preferences and compute stable matc…
Approximate-EFX Allocations with Ordinal and Limited Cardinal Information
Aris Filos-Ratsikas, Georgios Kalantzis, Alexandros A. Voudouris
We study a discrete fair division problem where agents have additive valuation functions over a set of goods. We focus on the well-known -EFX fairness criterion, accordi…
Equilibrium Computation in First-Price Auctions with Correlated Priors
Aris Filos-Ratsikas, Yiannis Giannakopoulos, Alexandros Hollender +1
We consider the computational complexity of computing Bayes-Nash equilibria in first-price auctions, where the bidders' values for the item are drawn from a general (possibly corre…
Utilitarian Distortion with Predictions
Aris Filos-Ratsikas, Georgios Kalantzis, Alexandros A. Voudouris
We study the utilitarian distortion of social choice mechanisms under the recently proposed learning-augmented framework where some (possibly unreliable) predicted information abou…
Optimal Metric Distortion for Matching on the Line
Aris Filos-Ratsikas, Vasilis Gkatzelis, Mohamad Latifian +2
We study the distortion of one-sided and two-sided matching problems on the line. In the one-sided case, agents need to be matched to items, and each agent's cost in a matc…
Pushing the Frontier on Approximate EFX Allocations
Georgios Amanatidis, Aris Filos-Ratsikas, Alkmini Sgouritsa
We study the problem of allocating a set of indivisible goods to a set of agents with additive valuation functions, aiming to achieve approximate envy-freeness up to any good (-…
On the Computation of Equilibria in Discrete First-Price Auctions
Aris Filos-Ratsikas, Yiannis Giannakopoulos, Alexandros Hollender +1
We study the computational complexity of computing Bayes-Nash equilibria in first-price auctions with discrete value distributions and discrete bidding space, under general subject…
PPAD-membership for Problems with Exact Rational Solutions: A General Approach via Convex Optimization
Aris Filos-Ratsikas, Kristoffer Arnsfelt Hansen, Kasper Høgh +1
We introduce a general technique for proving membership of search problems with exact rational solutions in PPAD, one of the most well-known classes containing total search problem…
On the Potential and Limitations of Proxy Voting: Delegation with Incomplete Votes
Georgios Amanatidis, Aris Filos-Ratsikas, Philip Lazos +2
We study elections where voters are faced with the challenge of expressing preferences over an extreme number of issues under consideration. This is largely motivated by emerging b…
Truthful Interval Covering
Argyrios Deligkas, Aris Filos-Ratsikas, Alexandros A. Voudouris
We initiate the study of a novel problem in mechanism design without money, which we term Truthful Interval Covering (TIC). An instance of TIC consists of a set of agents each asso…
Improved Metric Distortion via Threshold Approvals
Elliot Anshelevich, Aris Filos-Ratsikas, Christopher Jerrett +1
We consider a social choice setting in which agents and alternatives are represented by points in a metric space, and the cost of an agent for an alternative is the distance betwee…
Revisiting the Distortion of Distributed Voting
Aris Filos-Ratsikas, Alexandros A. Voudouris
We consider a setting with agents that have preferences over alternatives and are partitioned into disjoint districts. The goal is to choose one alternative as the winner using a m…
Settling the Distortion of Distributed Facility Location
Aris Filos-Ratsikas, Panagiotis Kanellopoulos, Alexandros A. Voudouris +1
We study the distributed facility location problem, where a set of agents with positions on the line of real numbers are partitioned into disjoint districts, and the goal is to cho…
Fair Division of Indivisible Goods: Recent Progress and Open Questions
Georgios Amanatidis, Haris Aziz, Georgios Birmpas +5
Allocating resources to individuals in a fair manner has been a topic of interest since ancient times, with most of the early mathematical work on the problem focusing on resources…
Fair Division of Indivisible Goods: A Survey
Georgios Amanatidis, Georgios Birmpas, Aris Filos-Ratsikas +1
Allocating resources to individuals in a fair manner has been a topic of interest since the ancient times, with most of the early rigorous mathematical work on the problem focusing…
FIXP-membership via Convex Optimization: Games, Cakes, and Markets
Aris Filos-Ratsikas, Kristoffer Arnsfelt Hansen, Kasper Høgh +1
We introduce a new technique for proving membership of problems in FIXP - the class capturing the complexity of computing a fixed-point of an algebraic circuit. Our technique const…