U3. This is only true for constant-sum games. There are numerous games in which both can win, for
example, two investors purchasing stock in the same company can both win as the stock price increases.
U4. Before answering the subquestions, it helps to calculate the probability of each player winning or
losing. The probability of winning and losing for Confucius is identical to the probability for Bob.
(a) For Alice, the probability of having all heads is 0.5 • 0.5 • 0.5 = 0.125, and the probability
(c) For Confucius, there are three ways to have two heads and one tail land: the first quarter
could be the tail, the second quarter could be the tail, or the third quarter could be the tail. The probability
(d) The payoff of Confucius is 0.375 • 2 + 0.625 • –1 = 0.125.
Games of Strategy, Fourth Edition Copyright © 2015 W. W. Norton & Company