Search Results for author: Toby Walsh

Found 51 papers, 1 papers with code

Nash Welfare and Facility Location

no code implementations6 Oct 2023 Alexander Lam, Haris Aziz, Toby Walsh

We consider the problem of locating a facility to serve a set of agents located along a line.

Fairness

Mechanisms that play a game, not toss a coin

no code implementations21 Aug 2023 Toby Walsh

We propose a number of novel derandomized mechanisms for these six domains with good normative properties.

Incentives to Offer Algorithmic Recourse

no code implementations27 Jan 2023 Matthew Olckers, Toby Walsh

Due to the importance of artificial intelligence (AI) in a variety of high-stakes decisions, such as loan approval, job hiring, and criminal bail, researchers in Explainable AI (XAI) have developed algorithms to provide users with recourse for an unfavorable outcome.

Explainable Artificial Intelligence (XAI)

Proportional Fairness in Obnoxious Facility Location

no code implementations11 Jan 2023 Haris Aziz, Alexander Lam, Bo Li, Fahimeh Ramezani, Toby Walsh

On the other hand, in the randomized setting, we identify proportionally fair and strategyproof mechanisms that give an expected welfare within a constant factor of the optimal welfare.

Fairness

Manipulation and Peer Mechanisms: A Survey

no code implementations5 Oct 2022 Matthew Olckers, Toby Walsh

In peer mechanisms, the competitors for a prize also determine who wins.

Random Rank: The One and Only Strategyproof and Proportionally Fair Randomized Facility Location Mechanism

no code implementations30 May 2022 Haris Aziz, Alexander Lam, Mashbat Suzuki, Toby Walsh

Proportionality is an attractive fairness concept that has been applied to a range of problems including the facility location problem, a classic problem in social choice.

Fairness

The Meta-Turing Test

no code implementations11 May 2022 Toby Walsh

These refinements could be applied also to Turing's original imitation game.

Fairness Amidst Non-IID Graph Data: Current Achievements and Future Directions

no code implementations15 Feb 2022 Wenbin Zhang, SHimei Pan, Shuigeng Zhou, Toby Walsh, Jeremy C. Weiss

The importance of understanding and correcting algorithmic bias in machine learning (ML) has led to an increase in research on fairness in ML, which typically assumes that the underlying data is independent and identically distributed (IID).

Fairness

Strategyproof and Proportionally Fair Facility Location

no code implementations2 Nov 2021 Haris Aziz, Alexander Lam, Barton E. Lee, Toby Walsh

We show that imposing strategyproofness renders many of the axioms to be equivalent: the family of mechanisms that satisfy proportionality, unanimity, and strategyproofness is equivalent to the family of mechanisms that satisfy UFS and strategyproofness, which, in turn, is equivalent to the family of mechanisms that satisfy PF and strategyproofness.

Fairness

Strategy Proof Mechanisms for Facility Location with Capacity Limits

no code implementations17 Sep 2020 Toby Walsh

An important feature of many real world facility location problems are capacity limits on the facilities.

Strategy Proof Mechanisms for Facility Location in Euclidean and Manhattan Space

no code implementations17 Sep 2020 Toby Walsh

We study the impact on mechanisms for facility location of moving from one dimension to two (or more) dimensions and Euclidean or Manhattan distances.

Fairness

Strategy Proof Mechanisms for Facility Location at Limited Locations

no code implementations17 Sep 2020 Toby Walsh

Facility location problems often permit facilities to be located at any position.

Position

Adventures in Mathematical Reasoning

no code implementations20 Aug 2020 Toby Walsh

"Mathematics is not a careful march down a well-cleared highway, but a journey into a strange wilderness, where the explorers often get lost.

Mathematical Reasoning

On the Complexity of Breaking Symmetry

no code implementations16 May 2020 Toby Walsh

We can break symmetry by eliminating solutions within a symmetry class that are not least in the lexicographical ordering.

Fair Division: The Computer Scientist's Perspective

no code implementations11 May 2020 Toby Walsh

I survey recent progress on a classic and challenging problem in social choice: the fair division of indivisible items.

A Pebble in the AI Race

no code implementations30 Mar 2020 Toby Walsh

Bhutan is sometimes described as \a pebble between two boulders", a small country caught between the two most populous nations on earth: India and China.

From Matching with Diversity Constraints to Matching with Regional Quotas

no code implementations17 Feb 2020 Haris Aziz, Serge Gaspers, Zhaohong Sun, Toby Walsh

In this paper, we present a polynomial-time reduction to transform an instance of (1) to an instance of (2) and we show how the feasibility and stability of corresponding matchings are preserved under the reduction.

Greedy Algorithms for Fair Division of Mixed Manna

no code implementations25 Nov 2019 Martin Aleksandrov, Toby Walsh

For example, we show that maximizing the Nash welfare with mixed manna (or minimizing the disutility Nash welfare) does not ensure an EF1 allocation whereas with goods and the Nash welfare it does.

Fairness

Facility Location Problem with Capacity Constraints: Algorithmic and Mechanism Design Perspectives

no code implementations22 Nov 2019 Haris Aziz, Hau Chan, Barton E. Lee, Bo Li, Toby Walsh

From the algorithmic perspective, we prove that the corresponding optimization problem, where the goal is to locate facilities to minimize either the total cost to all agents or the maximum cost of any agent is NP-hard.

Online Fair Division: A Survey

no code implementations21 Nov 2019 Martin Aleksandrov, Toby Walsh

We survey a burgeoning and promising new research area that considers the online nature of many practical fair division problems.

A Commentary on "Breaking Row and Column Symmetries in Matrix Models"

no code implementations3 Oct 2019 Alan M. Frisch, Brahim Hnich, Zeynep Kiziltan, Ian Miguel, Toby Walsh

The CP 2002 paper entitled "Breaking Row and Column Symmetries in Matrix Models" by Flener et al. (https://link. springer. com/chapter/10. 1007%2F3-540-46135-3_31) describes some of the first work for identifying and analyzing row and column symmetry in matrix models and for efficiently and effectively dealing with such symmetry using static symmetry-breaking ordering constraints.

CSPLib: Twenty Years On

no code implementations30 Sep 2019 Ian Gent, Toby Walsh

In 1999, we introduced CSPLib, a benchmark library for the constraints community.

Automated Theorem Proving BIG-bench Machine Learning

SAT vs CSP: a commentary

no code implementations27 Sep 2019 Toby Walsh

In 2000, I published a relatively comprehensive study of mappings between propositional satisfiability (SAT) and constraint satisfaction problems (CSPs) [Wal00].

Deceased Organ Matching in Australia

no code implementations18 Oct 2017 Toby Walsh

Despite efforts to increase the supply of organs from living donors, most kidney transplants performed in Australia still come from deceased donors.

Verifying Properties of Binarized Deep Neural Networks

no code implementations19 Sep 2017 Nina Narodytska, Shiva Prasad Kasiviswanathan, Leonid Ryzhyk, Mooly Sagiv, Toby Walsh

To the best of our knowledge, this is the first work on verifying properties of deep neural networks using an exact Boolean encoding of the network.

Image Classification

Expert and Non-Expert Opinion about Technological Unemployment

no code implementations21 Jun 2017 Toby Walsh

To look into this issue in more depth, we surveyed experts in Robotics and AI about the risk, and compared their views with those of non-experts.

The Conference Paper Assignment Problem: Using Order Weighted Averages to Assign Indivisible Goods

no code implementations19 May 2017 Jing Wu Lian, Nicholas Mattei, Renee Noble, Toby Walsh

Motivated by the common academic problem of allocating papers to referees for conference reviewing we propose a novel mechanism for solving the assignment problem when we have a two sided matching problem with preferences from one side (the agents/reviewers) over the other side (the objects/papers) and both sides have capacity constraints.

Decision Making

Ethical Considerations in Artificial Intelligence Courses

no code implementations26 Jan 2017 Emanuelle Burton, Judy Goldsmith, Sven Koenig, Benjamin Kuipers, Nicholas Mattei, Toby Walsh

The recent surge in interest in ethics in artificial intelligence may leave many educators wondering how to address moral, ethical, and philosophical issues in their AI courses.

Ethics

Empirical Evaluation of Real World Tournaments

no code implementations3 Aug 2016 Nicholas Mattei, Toby Walsh

Computational Social Choice (ComSoc) is a rapidly developing field at the intersection of computer science, economics, social choice, and political science.

Interdependent Scheduling Games

no code implementations31 May 2016 Andres Abeliuk, Haris Aziz, Gerardo Berbeglia, Serge Gaspers, Petr Kalina, Nicholas Mattei, Dominik Peters, Paul Stursberg, Pascal Van Hentenryck, Toby Walsh

We propose a model of interdependent scheduling games in which each player controls a set of services that they schedule independently.

Scheduling

The Singularity May Never Be Near

no code implementations20 Feb 2016 Toby Walsh

There is both much optimism and pessimism around artificial intelligence (AI) today.

Welfare of Sequential Allocation Mechanisms for Indivisible Goods

no code implementations26 Nov 2015 Haris Aziz, Thomas Kalinowski, Toby Walsh, Lirong Xia

Sequential allocation is a simple and attractive mechanism for the allocation of indivisible goods.

Turing's Red Flag

no code implementations30 Oct 2015 Toby Walsh

Sometime in the future we will have to deal with the impact of AI's being mistaken for humans.

Online Fair Division: analysing a Food Bank problem

no code implementations26 Feb 2015 Martin Aleksandrov, Haris Aziz, Serge Gaspers, Toby Walsh

We study an online model of fair division designed to capture features of a real world charity problem.

Possible and Necessary Allocations via Sequential Mechanisms

no code implementations6 Dec 2014 Haris Aziz, Toby Walsh, Lirong Xia

We focus on possible and necessary allocation problems, checking whether allocations of a given form occur in some or all mechanisms for several commonly used classes of sequential allocation mechanisms.

A Study of Proxies for Shapley Allocations of Transport Costs

no code implementations21 Aug 2014 Haris Aziz, Casey Cahan, Charles Gretton, Phillip Kilby, Nicholas Mattei, Toby Walsh

We propose and evaluate a number of solutions to the problem of calculating the cost to serve each location in a single-vehicle transport setting.

Computational Aspects of Multi-Winner Approval Voting

no code implementations11 Jul 2014 Haris Aziz, Serge Gaspers, Joachim Gudmundsson, Simon Mackenzie, Nicholas Mattei, Toby Walsh

We study computational aspects of three prominent voting rules that use approval ballots to elect multiple winners.

Allocation in Practice

no code implementations11 Jul 2014 Toby Walsh

In the first, we have been working with FoodBank Local, a social startup working in collaboration with food bank charities around the world to optimise the logistics of collecting and distributing donated food.

The Computational Impact of Partial Votes on Strategic Voting

no code implementations28 May 2014 Nina Narodytska, Toby Walsh

These methods modify scoring rules (like the Borda count), elimination style rules (like single transferable vote) and rules based on the tournament graph (like Copeland) respectively.

The PeerRank Method for Peer Assessment

no code implementations28 May 2014 Toby Walsh

Since the grade of an agent is a measure of their ability to grade correctly, the PeerRank method weights grades by the grades of the grading agent.

Fair assignment of indivisible objects under ordinal preferences

no code implementations23 Dec 2013 Haris Aziz, Serge Gaspers, Simon Mackenzie, Toby Walsh

The computational complexity of checking whether a fair assignment exists is studied for these fairness notions.

Fairness Open-Ended Question Answering

Breaking Symmetry with Different Orderings

no code implementations21 Jun 2013 Nina Narodytska, Toby Walsh

We can break symmetry by eliminating solutions within each symmetry class.

How Hard Is It to Control an Election by Breaking Ties?

no code implementations23 Apr 2013 Nicholas Mattei, Nina Narodytska, Toby Walsh

Indeed, we prove that it can be NP-hard to control an election by breaking ties even with a two-stage voting rule.

A Social Welfare Optimal Sequential Allocation Procedure

no code implementations22 Apr 2013 Thomas Kalinowski, Nina Nardoytska, Toby Walsh

We consider a simple sequential allocation procedure for sharing indivisible items between agents in which agents take turns to pick items.

Three Generalizations of the FOCUS Constraint

no code implementations22 Apr 2013 Nina Narodytska, Thierry Petit, Mohamed Siala, Toby Walsh

The FOCUS constraint expresses the notion that solutions are concentrated.

Coalitional Manipulation for Schulze's Rule

no code implementations3 Apr 2013 Serge Gaspers, Thomas Kalinowski, Nina Narodytska, Toby Walsh

Schulze's rule is used in the elections of a large number of organizations including Wikimedia and Debian.

Open-Ended Question Answering

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