Game Connectivity and Adaptive Dynamics

Fuente: arXiv
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Main Authors: Johnston, Tom, Savery, Michael, Scott, Alex, Tarbush, Bassel
Format: Preprint
Published: 2023
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author Johnston, Tom
Savery, Michael
Scott, Alex
Tarbush, Bassel
author_facet Johnston, Tom
Savery, Michael
Scott, Alex
Tarbush, Bassel
contents We analyse the typical structure of games in terms of the connectivity properties of their best-response graphs. Our central result shows that, among games that are `generic' (without indifferences) and that have a pure Nash equilibrium, all but a small fraction are \emph{connected}, meaning that every action profile that is not a pure Nash equilibrium can reach every pure Nash equilibrium via best-response paths. This has important implications for dynamics in games. In particular, we show that there are simple, uncoupled, adaptive dynamics for which period-by-period play converges almost surely to a pure Nash equilibrium in all but a small fraction of generic games that have one (which contrasts with the known fact that there is no such dynamic that leads almost surely to a pure Nash equilibrium in \emph{every} generic game that has one). We build on recent results in probabilistic combinatorics for our characterisation of game connectivity.
format Preprint
id arxiv_https___arxiv_org_abs_2309_10609
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Game Connectivity and Adaptive Dynamics
Johnston, Tom
Savery, Michael
Scott, Alex
Tarbush, Bassel
Theoretical Economics
Computer Science and Game Theory
Combinatorics
We analyse the typical structure of games in terms of the connectivity properties of their best-response graphs. Our central result shows that, among games that are `generic' (without indifferences) and that have a pure Nash equilibrium, all but a small fraction are \emph{connected}, meaning that every action profile that is not a pure Nash equilibrium can reach every pure Nash equilibrium via best-response paths. This has important implications for dynamics in games. In particular, we show that there are simple, uncoupled, adaptive dynamics for which period-by-period play converges almost surely to a pure Nash equilibrium in all but a small fraction of generic games that have one (which contrasts with the known fact that there is no such dynamic that leads almost surely to a pure Nash equilibrium in \emph{every} generic game that has one). We build on recent results in probabilistic combinatorics for our characterisation of game connectivity.
title Game Connectivity and Adaptive Dynamics
topic Theoretical Economics
Computer Science and Game Theory
Combinatorics
url https://arxiv.org/abs/2309.10609