Subgame-perfect equilibrium strategies for time-inconsistent recursive stochastic control problems

Fuente: arXiv
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Autores principales: Mastrogiacomo, Elisa, Tarsia, Marco
Formato: Preprint
Publicado: 2023
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author Mastrogiacomo, Elisa
Tarsia, Marco
author_facet Mastrogiacomo, Elisa
Tarsia, Marco
contents We study time-inconsistent recursive stochastic control problems, i.e., for which the Bellman principle of optimality does not hold. For this class of problems classical optimal controls may fail to exist, or to be relevant in practice, and dynamic programming is not easily applicable. Therefore, the notion of optimality is defined through a game-theoretic framework by means of subgame perfect equilibrium: we interpret our preference changes which, realistically, are inconsistent over time, as players in a game for which we want to find a Nash equilibrium. The approach followed in our work relies on the stochastic (Pontryagin) maximum principle: we adapt the classical spike variation technique to obtain a characterisation of equilibrium strategies in terms of a generalised second-order Hamiltonian function defined through pairs of backward stochastic differential equations, even in the multidimensional case. The theoretical results are applied in the financial field to finite horizon investment-consumption policies with non-exponential actualisation. Here the existence of non-trivial equilibrium policies is also ascertained.
format Preprint
id arxiv_https___arxiv_org_abs_2302_00471
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Subgame-perfect equilibrium strategies for time-inconsistent recursive stochastic control problems
Mastrogiacomo, Elisa
Tarsia, Marco
Optimization and Control
60H30, 91A23, 91B70, 93E20
We study time-inconsistent recursive stochastic control problems, i.e., for which the Bellman principle of optimality does not hold. For this class of problems classical optimal controls may fail to exist, or to be relevant in practice, and dynamic programming is not easily applicable. Therefore, the notion of optimality is defined through a game-theoretic framework by means of subgame perfect equilibrium: we interpret our preference changes which, realistically, are inconsistent over time, as players in a game for which we want to find a Nash equilibrium. The approach followed in our work relies on the stochastic (Pontryagin) maximum principle: we adapt the classical spike variation technique to obtain a characterisation of equilibrium strategies in terms of a generalised second-order Hamiltonian function defined through pairs of backward stochastic differential equations, even in the multidimensional case. The theoretical results are applied in the financial field to finite horizon investment-consumption policies with non-exponential actualisation. Here the existence of non-trivial equilibrium policies is also ascertained.
title Subgame-perfect equilibrium strategies for time-inconsistent recursive stochastic control problems
topic Optimization and Control
60H30, 91A23, 91B70, 93E20
url https://arxiv.org/abs/2302.00471