来自《耶鲁大学开放课程：博弈论 第9集 第9集》

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  Is that right?
  是这样吧
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  So since Serena's backhand has improved,
  既然维纳斯的反手水平提高了
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  Venus is going to hit it to Serena's backhand less often than before,
  维纳斯会减少打塞丽娜反手的概率
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  and that might make Serena less inclined to cheat towards her backhand
  这样就降低了维纳斯倾向反手方向的概率
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  because the ball is coming that way less often.
  因为反手方向的球变少了
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  So this is a indirect or a strategic effect.
  这个叫间接影响或者战略影响
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  The strategic effect is Venus hits L less often,
  战略影响就是维纳斯选L的概率降低了
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  so Serena should reduce the number of times that she leans to the left
  因此塞丽娜倾向左侧的次数也减少了
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  because the ball is coming that way fewer times.
  因为反手方向的球也减少了
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  Now notice that these two effects go in opposite directions, is that right?
  请注意这是两种完全相反的结果 是吧
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  One of them tends to argue that Q would go up, that's the direct effect
  直接影响认为Q会增大
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  and the other one is more subtle,
  另一个影响比较严密