10,629 research outputs found
Imitative Follower Deception in Stackelberg Games
Information uncertainty is one of the major challenges facing applications of
game theory. In the context of Stackelberg games, various approaches have been
proposed to deal with the leader's incomplete knowledge about the follower's
payoffs, typically by gathering information from the leader's interaction with
the follower. Unfortunately, these approaches rely crucially on the assumption
that the follower will not strategically exploit this information asymmetry,
i.e., the follower behaves truthfully during the interaction according to their
actual payoffs. As we show in this paper, the follower may have strong
incentives to deceitfully imitate the behavior of a different follower type
and, in doing this, benefit significantly from inducing the leader into
choosing a highly suboptimal strategy. This raises a fundamental question: how
to design a leader strategy in the presence of a deceitful follower? To answer
this question, we put forward a basic model of Stackelberg games with
(imitative) follower deception and show that the leader is indeed able to
reduce the loss due to follower deception with carefully designed policies. We
then provide a systematic study of the problem of computing the optimal leader
policy and draw a relatively complete picture of the complexity landscape;
essentially matching positive and negative complexity results are provided for
natural variants of the model. Our intractability results are in sharp contrast
to the situation with no deception, where the leader's optimal strategy can be
computed in polynomial time, and thus illustrate the intrinsic difficulty of
handling follower deception. Through simulations we also examine the benefit of
considering follower deception in randomly generated games
Markov Decision Processes with Applications in Wireless Sensor Networks: A Survey
Wireless sensor networks (WSNs) consist of autonomous and resource-limited
devices. The devices cooperate to monitor one or more physical phenomena within
an area of interest. WSNs operate as stochastic systems because of randomness
in the monitored environments. For long service time and low maintenance cost,
WSNs require adaptive and robust methods to address data exchange, topology
formulation, resource and power optimization, sensing coverage and object
detection, and security challenges. In these problems, sensor nodes are to make
optimized decisions from a set of accessible strategies to achieve design
goals. This survey reviews numerous applications of the Markov decision process
(MDP) framework, a powerful decision-making tool to develop adaptive algorithms
and protocols for WSNs. Furthermore, various solution methods are discussed and
compared to serve as a guide for using MDPs in WSNs
Designing the Game to Play: Optimizing Payoff Structure in Security Games
Effective game-theoretic modeling of defender-attacker behavior is becoming
increasingly important. In many domains, the defender functions not only as a
player but also the designer of the game's payoff structure. We study
Stackelberg Security Games where the defender, in addition to allocating
defensive resources to protect targets from the attacker, can strategically
manipulate the attacker's payoff under budget constraints in weighted L^p-norm
form regarding the amount of change. Focusing on problems with weighted
L^1-norm form constraint, we present (i) a mixed integer linear program-based
algorithm with approximation guarantee; (ii) a branch-and-bound based algorithm
with improved efficiency achieved by effective pruning; (iii) a polynomial time
approximation scheme for a special but practical class of problems. In
addition, we show that problems under budget constraints in L^0-norm form and
weighted L^\infty-norm form can be solved in polynomial time. We provide an
extensive experimental evaluation of our proposed algorithms
Defeating jamming with the power of silence: a game-theoretic analysis
The timing channel is a logical communication channel in which information is
encoded in the timing between events. Recently, the use of the timing channel
has been proposed as a countermeasure to reactive jamming attacks performed by
an energy-constrained malicious node. In fact, whilst a jammer is able to
disrupt the information contained in the attacked packets, timing information
cannot be jammed and, therefore, timing channels can be exploited to deliver
information to the receiver even on a jammed channel.
Since the nodes under attack and the jammer have conflicting interests, their
interactions can be modeled by means of game theory. Accordingly, in this paper
a game-theoretic model of the interactions between nodes exploiting the timing
channel to achieve resilience to jamming attacks and a jammer is derived and
analyzed. More specifically, the Nash equilibrium is studied in the terms of
existence, uniqueness, and convergence under best response dynamics.
Furthermore, the case in which the communication nodes set their strategy and
the jammer reacts accordingly is modeled and analyzed as a Stackelberg game, by
considering both perfect and imperfect knowledge of the jammer's utility
function. Extensive numerical results are presented, showing the impact of
network parameters on the system performance.Comment: Anti-jamming, Timing Channel, Game-Theoretic Models, Nash Equilibriu
On the Hardness of Signaling
There has been a recent surge of interest in the role of information in
strategic interactions. Much of this work seeks to understand how the realized
equilibrium of a game is influenced by uncertainty in the environment and the
information available to players in the game. Lurking beneath this literature
is a fundamental, yet largely unexplored, algorithmic question: how should a
"market maker" who is privy to additional information, and equipped with a
specified objective, inform the players in the game? This is an informational
analogue of the mechanism design question, and views the information structure
of a game as a mathematical object to be designed, rather than an exogenous
variable.
We initiate a complexity-theoretic examination of the design of optimal
information structures in general Bayesian games, a task often referred to as
signaling. We focus on one of the simplest instantiations of the signaling
question: Bayesian zero-sum games, and a principal who must choose an
information structure maximizing the equilibrium payoff of one of the players.
In this setting, we show that optimal signaling is computationally intractable,
and in some cases hard to approximate, assuming that it is hard to recover a
planted clique from an Erdos-Renyi random graph. This is despite the fact that
equilibria in these games are computable in polynomial time, and therefore
suggests that the hardness of optimal signaling is a distinct phenomenon from
the hardness of equilibrium computation. Necessitated by the non-local nature
of information structures, en-route to our results we prove an "amplification
lemma" for the planted clique problem which may be of independent interest
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