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Ioannis Caragiannis

14 accepted papers

2026

Computing Approximately Proportional Allocations of Indivisible Goods: Beyond Additive and Monotone Valuations

AAAI 2026technical

Although approximate notions of envy-freeness—such as envy-freeness up to one good (EF1)—have been extensively studied for indivisible goods, the seemingly simpler fairness concept of proportionality up to one good (PROP1) has received far less attention. For additive valuations, every EF1 allocatio

Cited by 0SourcePDFScholar
2025

Welfare-Optimal Serial Dictatorships Have Polynomial Query Complexity

AAAI 2025technical

Serial dictatorship is a simple mechanism for coordinating agents in solving combinatorial optimization problems according to their preferences. The most representative such problem is one-sided matching, in which a set of n agents have values for a set of n items, and the objective is to compute a…

Cited by 0SourcePDFScholar
2024

Low-Distortion Clustering with Ordinal and Limited Cardinal Information

AAAI 2024technical

Motivated by recent work in computational social choice, we extend the metric distortion framework to clustering problems. Given a set of n agents located in an underlying metric space, our goal is to partition them into k clusters, optimizing some social cost objective. The metric space is defined…

Cited by 7SourcePDFScholar
2023

New Fairness Concepts for Allocating Indivisible Items

IJCAI 2023poster

For the fundamental problem of fairly dividing a set of indivisible items among agents, envy-freeness up to any item (EFX) and maximin fairness (MMS) are arguably the most compelling fairness concepts proposed till now. Unfortunately, despite significant efforts over the past few years, whether EFX…

Cited by 15SourcePDFScholar
2022

Truthful Aggregation of Budget Proposals with Proportionality Guarantees

AAAI 2022technical

We study a participatory budgeting problem, where a set of strategic agents wish to split a divisible budget among different projects by aggregating their proposals on a single division. Unfortunately, the straightforward rule that divides the budget proportionally is susceptible to manipulation. Re…

Cited by 12SourcePDFScholar
2020

Evaluating Approval-Based Multiwinner Voting in Terms of Robustness to Noise

IJCAI 2020poster

Approval-based multiwinner voting rules have recently received much attention in the Computational Social Choice literature. Such rules aggregate approval ballots and determine a winning committee of alternatives. To assess effectiveness, we propose to employ new noise models that are specifically t…

Cited by 0SourcePDFScholar