Search Results for author: Lewis Hammond

Found 8 papers, 3 papers with code

On Imperfect Recall in Multi-Agent Influence Diagrams

no code implementations11 Jul 2023 James Fox, Matt MacDermott, Lewis Hammond, Paul Harrenstein, Alessandro Abate, Michael Wooldridge

Multi-agent influence diagrams (MAIDs) are a popular game-theoretic model based on Bayesian networks.

Reasoning about Causality in Games

no code implementations5 Jan 2023 Lewis Hammond, James Fox, Tom Everitt, Ryan Carey, Alessandro Abate, Michael Wooldridge

Regarding question iii), we describe correspondences between causal games and other formalisms, and explain how causal games can be used to answer queries that other causal or game-theoretic models do not support.

Lexicographic Multi-Objective Reinforcement Learning

1 code implementation28 Dec 2022 Joar Skalse, Lewis Hammond, Charlie Griffin, Alessandro Abate

In this work we introduce reinforcement learning techniques for solving lexicographic multi-objective problems.

Multi-Objective Reinforcement Learning reinforcement-learning

Observational Robustness and Invariances in Reinforcement Learning via Lexicographic Objectives

no code implementations30 Sep 2022 Daniel Jarne Ornia, Licio Romao, Lewis Hammond, Manuel Mazo Jr., Alessandro Abate

Policy gradient algorithms that have strong convergence guarantees are usually modified to obtain robust policies in ways that do not preserve algorithm guarantees, which defeats the purpose of formal robustness requirements.

reinforcement-learning Reinforcement Learning (RL)

Rational Verification for Probabilistic Systems

no code implementations19 Jul 2021 Julian Gutierrez, Lewis Hammond, Anthony W. Lin, Muhammad Najib, Michael Wooldridge

Rational verification is the problem of determining which temporal logic properties will hold in a multi-agent system, under the assumption that agents in the system act rationally, by choosing strategies that collectively form a game-theoretic equilibrium.

Equilibrium Refinements for Multi-Agent Influence Diagrams: Theory and Practice

1 code implementation9 Feb 2021 Lewis Hammond, James Fox, Tom Everitt, Alessandro Abate, Michael Wooldridge

Multi-agent influence diagrams (MAIDs) are a popular form of graphical model that, for certain classes of games, have been shown to offer key complexity and explainability advantages over traditional extensive form game (EFG) representations.

Multi-Agent Reinforcement Learning with Temporal Logic Specifications

1 code implementation1 Feb 2021 Lewis Hammond, Alessandro Abate, Julian Gutierrez, Michael Wooldridge

In this paper, we study the problem of learning to satisfy temporal logic specifications with a group of agents in an unknown environment, which may exhibit probabilistic behaviour.

Multi-agent Reinforcement Learning reinforcement-learning +1

Learning Tractable Probabilistic Models for Moral Responsibility and Blame

no code implementations8 Oct 2018 Lewis Hammond, Vaishak Belle

From the viewpoint of such systems, the urgent questions are: (a) How can models of moral scenarios and blameworthiness be extracted and learnt automatically from data?

Decision Making Management +2

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