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Mathematical Journeys - Saint Ann's School

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26
 
<br />

THE REALITY GAME<br />

JOSHUA GLASSER<br />

ABSTRACT. Focusing on the intricacies of variants of the Reality game, this paper<br />

explores the different mathematical constructs used to interpret such a game. Through<br />

MatLab simulations and algebraic equations, this paper attempts to explain some of the<br />

phenomena that occur as a result of the Reality game.<br />

The reality Game, although less than a decade old, has already been the focal<br />

point of a few major studies, Including Farmar’s ubiquitous paper describing it. Though<br />

there have been many variations as to what in particular constitutes the reality game,<br />

many agree that it is a game in which any number of players bet money on a coin whose<br />

probability of landing on either heads or tails are as follows:<br />

1.N players bet X amount of money each on heads or tails We varied this<br />

eventually, but it was true in the beginning.<br />

2. The probability of the coin landing on either heads or tails is a result of X-plus<br />

over X total bet. X + is defined as … x + / Xtotalbet<br />

3. The winners receive an equal take of the pot.<br />

We then proceeded to have the players employ any of the following 8 strategies:<br />

S1. Bet always on the same outcome.<br />

!<br />

!<br />

S2. Bet on the outcome that came up in the last round.<br />

S3. Bet on the outcome that didn't come up in the last round.<br />

S4. Bet according to the monetary majority in the last round.<br />

S5. Bet according to the monetary minority in the last round.<br />

S6. Bet according to the numerical majority in the last round.<br />

S7. Bet according to the numerical minority in the last round.<br />

S8. Bet randomly, H or T with probability 1/2 each. This is closer to the original paper<br />

(Farmer et.al.), except that they allowed probabilities other than !.<br />

To see the pure results of these strategies, we simplified the number bet to a constant 1<br />

unit throughout runs. While some advantages seemed to appear, they were contained in<br />

limited runs of 100 or 1000 tosses. More even distributions of bets often led to more<br />

even results as well, with much more varied results regarding cumulative P&L’s.<br />

After building some experience with the behavior of these strategies, we decided<br />

to embark on an analytical investigation of the expected winnings of players following<br />

different strategies in a setting where everyone bets the same amount, in order to<br />

disaggregate the effects of the amount and the direction of each bet. To begin with, we<br />

studied the "pure strategies", i.e. the situations where all N players follow the same<br />

strategy. The only pure strategies that make sense are 1 and 8. For the case of pure<br />

strategy 1, let there be N + players betting +1 and N - N + players betting -1. Then the<br />

expected winnings of a +1 player is E[P + ] = (N + /N)(N/N + - 1) - (1 - N + /N) = 0.<br />


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