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(http://www.math.ucla.edu/~tom/papers/poker1.pdf) discusses<br />

Borel's and von neumann's models of two-person,<br />

zero-sum poker with bluffing, which were published in the<br />

1930s. John nash's 1950 dissertation (http://www.princeton.<br />

edu/mudd/news/faq/topics/non-Cooperative_Games_nash.<br />

pdf, scan of the original, page 32) contains a simple poker<br />

game in which agents can bluff, opening with some probability<br />

even when they have bad cards. of course, there is nothing<br />

intrinsic in choosing to open that says, "I have good cards;" it<br />

is just an action in the game. And, in equilibrium, your opponent<br />

knows exactly what the probability is that you have<br />

a good hand when you "claim to." The reason that he can't<br />

completely disregard the claim is that you sometimes behave<br />

aggressively when you Do have a good hand. In these simple,<br />

static (one period) models of lying, the credibility of the bluff<br />

is supported by the possibility that it is not a bluff.<br />

The more modern literature has focused on dynamic<br />

(multi-period) models, in which one can tell more elaborate<br />

stories about "building and destroying credibility." one standard<br />

approach can be illustrated by a classic model introduced<br />

by Joel Sobel in the article "A Theory of Credibility" [Review<br />

of Economic Studies (1985) 52(4) pp. 557-573]. There are two<br />

agents: a king and a spy. The king is unsure about the motivations<br />

of the spy, who might want to help the king or might<br />

be a double agent whose motivations are exactly opposed to<br />

those of the king. every month, a diplomatic issue comes up<br />

with its own level of importance. The spy observes what would<br />

be best for the king and advises an action (say, A or B). After<br />

the action, the king learns whether it was the right action to<br />

take.<br />

In equilibrium, a double agent builds credibility by giving<br />

the king good advice for a while. Then he advises the king to<br />

do the wrong thing for the king when a sufficiently important<br />

issue comes up. After that, the double agent has been outed,<br />

but has benefited in one high-stakes issue.<br />

This illustrates many of the standard ingredients in economic<br />

models of deception:<br />

• Asymmetric information: at least one agent's "type" or motivation<br />

is unknown to the other(s).<br />

225

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