来自《耶鲁大学开放课程：博弈论 第9集 第9集》

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  So in particular,
  具体点说
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  we're going to use the notation Pi(Si) to be the probability
  我们用Pi(Si)表示在混合策略Pi下
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  www.YYeTs.net
  人人影视
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  that Player I plays Si given that he's mixing using Pi.
  参与人I采用策略Si的概率
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  So Pi(Si) is the probability that Pi assigns to the pure strategy Si.
  即Pi(Si)是Pi赋予纯策略Si的概率
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  Let's immediately refer that back to our example.
  我们用上一讲的例子来解释一下
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  So for example, if I'm playing (1/3, 1/3, 1/3)
  比如在“石头剪刀布”中
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  in rock, paper, scissors
  我采用(1/3, 1/3, 1/3)的混合策略
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  then Pi is (1/3, 1/3, 1/3)
  那么Pi就是(1/3, 1/3, 1/3)
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  and Pi of rock, so Pi(R)--is a 1/3.
  选择石头的概率即Pi(R)=1/3
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  So without belaboring it,
  我们就再不赘述了
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  that's all I'm doing here, is developing some notation.
  这就是我们要学会的符号表达法