166,701 research outputs found
Partially Observed Discrete-Time Risk-Sensitive Mean Field Games
In this paper, we consider discrete-time partially observed mean-field games
with the risk-sensitive optimality criterion. We introduce risk-sensitivity
behaviour for each agent via an exponential utility function. In the game
model, each agent is weakly coupled with the rest of the population through its
individual cost and state dynamics via the empirical distribution of states. We
establish the mean-field equilibrium in the infinite-population limit using the
technique of converting the underlying original partially observed stochastic
control problem to a fully observed one on the belief space and the dynamic
programming principle. Then, we show that the mean-field equilibrium policy,
when adopted by each agent, forms an approximate Nash equilibrium for games
with sufficiently many agents. We first consider finite-horizon cost function,
and then, discuss extension of the result to infinite-horizon cost in the
next-to-last section of the paper.Comment: 29 pages. arXiv admin note: substantial text overlap with
arXiv:1705.02036, arXiv:1808.0392
LQG Risk-Sensitive Mean Field Games with a Major Agent: A Variational Approach
Risk sensitivity plays an important role in the study of finance and
economics as risk-neutral models cannot capture and justify all economic
behaviors observed in reality. Risk-sensitive mean field game theory was
developed recently for systems where there exists a large number of
indistinguishable, asymptotically negligible and heterogeneous risk-sensitive
players, who are coupled via the empirical distribution of state across
population. In this work, we extend the theory of Linear Quadratic Gaussian
risk-sensitive mean-field games to the setup where there exists one major agent
as well as a large number of minor agents. The major agent has a significant
impact on each minor agent and its impact does not collapse with the increase
in the number of minor agents. Each agent is subject to linear dynamics with an
exponential-of-integral quadratic cost functional. Moreover, all agents
interact via the average state of minor agents (so-called empirical mean field)
and the major agent's state. We develop a variational analysis approach to
derive the best response strategies of agents in the limiting case where the
number of agents goes to infinity. We establish that the set of obtained
best-response strategies yields a Nash equilibrium in the limiting case and an
-Nash equilibrium in the finite player case. We conclude the paper
with an illustrative example
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