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Hauptverfasser: Foster, Harry, Knight, Vincent A., Krapohl, Sebastian
Format: Preprint
Veröffentlicht: 2026
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Online-Zugang:https://arxiv.org/abs/2605.23513
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author Foster, Harry
Knight, Vincent A.
Krapohl, Sebastian
author_facet Foster, Harry
Knight, Vincent A.
Krapohl, Sebastian
contents Cooperation in heterogeneous groups, where individuals differ in resources, productivity, and behavioural responsiveness, underpins collective action across social and biological systems. Introspection dynamics, in which each player compares their payoff to their payoff under the alternative action, provides a natural learning rule for such asymmetric settings. Couto and Pal showed that for additive games, those in which the payoff difference a player evaluates when considering a switch is independent of the other players' actions, the stationary distribution of introspection dynamics is a product measure. We extend this result to introspection dynamics with mutation, where a selected player switches to a random action with some probability independent of payoffs, and with player-specific selection intensities. We show that the product structure is preserved, and we obtain the explicit per-player cooperation probability $p_i=ϕ_i(δ_i)(1-μ_{i0}-μ_{i1})+μ_{i0}$. We consider the heterogeneous public goods game, where $N$ players may differ in their contributions $α_i$, public goods multipliers $r_i$, and selection intensities $β_i$; the long-run cooperation probability admits the closed form $$ p_C = \frac{1}{N}\sum_{i=1}^{N} \left[\frac{1-μ_{i0}-μ_{i1}}{1+e^{\,β_iα_i(1-r_i/N)}}+μ_{i0}\right]. $$ Several structural consequences follow: a player-specific cooperation threshold at $r_i = N$ under symmetric mutation, a neutral-drift regime in which cooperation is governed entirely by mutation bias, and a mutation-selection balance in which aggregate cooperation is affine in the mutation rate, interpolating between the selection-driven level and neutrality. Mutation also regularises the strong-selection limit, so the closed form holds as $β_i\to\infty$, where the mutation-free dynamics degenerate.
format Preprint
id arxiv_https___arxiv_org_abs_2605_23513
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Introspection Dynamics with Mutation in Additive Games
Foster, Harry
Knight, Vincent A.
Krapohl, Sebastian
Computer Science and Game Theory
91A22, 91A26, 91A43, 60J10
G.3
Cooperation in heterogeneous groups, where individuals differ in resources, productivity, and behavioural responsiveness, underpins collective action across social and biological systems. Introspection dynamics, in which each player compares their payoff to their payoff under the alternative action, provides a natural learning rule for such asymmetric settings. Couto and Pal showed that for additive games, those in which the payoff difference a player evaluates when considering a switch is independent of the other players' actions, the stationary distribution of introspection dynamics is a product measure. We extend this result to introspection dynamics with mutation, where a selected player switches to a random action with some probability independent of payoffs, and with player-specific selection intensities. We show that the product structure is preserved, and we obtain the explicit per-player cooperation probability $p_i=ϕ_i(δ_i)(1-μ_{i0}-μ_{i1})+μ_{i0}$. We consider the heterogeneous public goods game, where $N$ players may differ in their contributions $α_i$, public goods multipliers $r_i$, and selection intensities $β_i$; the long-run cooperation probability admits the closed form $$ p_C = \frac{1}{N}\sum_{i=1}^{N} \left[\frac{1-μ_{i0}-μ_{i1}}{1+e^{\,β_iα_i(1-r_i/N)}}+μ_{i0}\right]. $$ Several structural consequences follow: a player-specific cooperation threshold at $r_i = N$ under symmetric mutation, a neutral-drift regime in which cooperation is governed entirely by mutation bias, and a mutation-selection balance in which aggregate cooperation is affine in the mutation rate, interpolating between the selection-driven level and neutrality. Mutation also regularises the strong-selection limit, so the closed form holds as $β_i\to\infty$, where the mutation-free dynamics degenerate.
title Introspection Dynamics with Mutation in Additive Games
topic Computer Science and Game Theory
91A22, 91A26, 91A43, 60J10
G.3
url https://arxiv.org/abs/2605.23513