hi folks so it's time to start into a 大家好，现在是时候开始
new topic and a very interesting one at 新话题，一个非常有趣的话题
that what we can talk about now is 我们现在可以谈论的是
repeated games and so this will use some 重复的游戏，所以这将使用一些
of the reasoning we've had in terms of 关于我们的推理
sub game perfect and extensive forms but 子游戏完美且广泛的形式，但
now think of situations where players 现在想到玩家
are playing a game but they're playing 在玩游戏，但他们在玩
it repeatedly over time so you know when 随着时间的推移反复出现，所以你知道什么时候
we think of most interactions in the 我们想到了大多数互动
world there's a lot of them which occur 世界上有很多发生
more than once so you know when we think 不止一次，所以您知道我们何时思考
about different kinds of things you know 关于你知道的各种事情
firms in a market place they're 他们在市场中的公司
interacting with their competitors 与竞争对手互动
they're doing it day after day after day 他们日复一日地在做
we think about political alliances 我们考虑政治联盟
countries deciding how they should 决定如何做的国家
negotiate with other ones whether they 与其他人协商是否
should should have conflicts and so 应该有冲突等等
forth those are things where you know 那些都是你所知道的
this happens repeatedly over time so 随着时间的推移反复发生
there's a long history and a long future 历史悠久，前途无限
ahead of them 在他们前面
friends you know do you exchange you 你认识的朋友你交换你
help your friends out when they need 在需要时帮助您的朋友
help do they help you back when you when 他们在你何时帮助你
you need it so you know you're going 你需要它，所以你知道你要去
through repeated interactions and how 通过反复的互动以及如何
you've performed in the past of your 你过去的表现
friends that have done very well for you 为您做得很好的朋友
you're more likely to reciprocate some 你更有可能回报一些
of these kinds of things can involve 这些事情可能涉及
repeated interactions workers team 反复互动的工人团队
production you've got a you know day 生产，你有一个你知道的一天
after day you need to help some of your 一天之后，您需要帮助一些
co-workers sometimes you have to do 同事有时您必须做
tasks that don't go noticed and 不会被注意到的任务
sometimes they do help you out and so 有时他们确实可以帮助您，所以
forth so these are situations where 第四，这些情况是
repetition can make a difference and 重复可以有所作为，
understanding it will be an important 了解这将是重要的
aspect of understanding how the 理解方面
repetition affects the play involves a 重复影响戏剧涉及
whole series of different kinds of 全系列的不同种类的
things I'm just to fix ideas let's talk 我只是为了解决问题而已
a little bit about OPEC which was a 关于欧佩克的一点点
cartel which was formed in the early 卡特尔成立于早期
1970s and and just in terms of 1970年代
background if you go back to you know 回到你知道的背景
the period between 1930 and up to 1973 从1930年到1973年
when OPEC started being put together the 当欧佩克开始放在一起时，
price of oil so these are all adjusted 石油价格，因此都进行了调整
numbers to reflect say two thousand and 要反映的数字说2000
eight dollars so we adjust for inflation 八美元，所以我们根据通货膨胀进行调整
and other kinds of things but if you 和其他种类的东西，但是如果你
just everything to the to the same 一切都一样
to adjust for inflation you get a price 调整通货膨胀，你会得到一个价格
of roughly $20 per barrel or less from 大约每桶20美元或更少
the period of 1930 through about 1973 从1930年到大约1973年
OPEC starts to form what happens they 欧佩克开始形成他们所发生的事情
decide that you know they've just been 决定你知道他们刚刚去过
acting it's a bunch of players a bunch 表演是一群玩家
of different producers they've been 他们曾经去过的不同制片人
acting on their own for many years and 独自行动多年
just pumping lots of oil and they pump 只是抽很多油，他们抽
so much oil that the prices is fairly 这么多的石油，价格合理
low it's very easy to buy oil so they're 低，买油很容易，所以他们
going to start by restricting production 首先要限制生产
cut production back down and that'll 减少生产，这将
drive the price up ok what's the 推动价格上涨，这是什么
difficulty is if all the other ones are 困难是所有其他的
producing very little and driving the 产生很少并驱动
price up 价格上涨
I'd like to cheat on the agreement and 我想在协议上作弊，
pump more oil so you can think of this 泵更多的油，所以你可以想到这个
as looking somewhat like a giant 看起来有点像巨人
prisoner's dilemma game where we'd all 我们都将在囚徒困境游戏中
like to pump less oil if we're OPEC or 如果我们是石油输出国组织（OPEC），则希望少抽油
oil producing countries drive the price 产油国拉动价格
up but we all have an incentive to cheat 起来，但我们都有诱骗的动机
a little bit and pump more oil and the 并抽更多的油
repetition can help us police that if 重复可以帮助我们报警，如果
for OPEC so what happens by 1976 the 对欧佩克而言，1976年发生了什么
price goes up to about $50 a barrel by 油价到了每桶约50美元
the time you get to 1982 these are also 你到1982年的时候
in real terms so that these are adjusted 实质性地调整这些
for inflation they've pumped up the 为了通货膨胀，他们加大了
price up to $90 a barrel and you know so 价格高达每桶90美元，你知道吗
it's in the early 1980s it does quite 在1980年代初期
well in terms of Oh packin lots of money 哦，哦，包装很多钱
coming in and then it collapses for a 进来然后崩溃了一个
while so when you look but the period 虽然如此，当你看，但时期
say between about 1986 to 2002 so 19 比如说在1986年到2002年之间，所以19
between 82 and 86 it starts to a road it 在82到86之间开始
kind of falls apart between 86 and 2002 在86和2002之间分崩离析
the price is basically $40 a barrel or 价格基本上是每桶40美元或
less and then they get back together 少然后他们重新聚在一起
again so actually during this period 再次如此实际上在此期间
there is a Iran Iraq war a whole series 有一场伊战全系列
of things go on in the Middle East that 在中东发生的事情
make it much more difficult to sustain 使维持变得更加困难
cooperation things deteriorate and then 合作的事情恶化然后
after a while you know things are 过了一会儿，你知道事情是
getting back in terms of higher prices 重新获得更高的价格
by late 2008 the price is pushed back up 到2008年底价格回升
to over $100 a barrel okay so what we 超过每桶100美元，那么我们
need to begin to understand this 需要开始了解这一点
understanding the repeated interaction 了解重复的互动
and understanding the motivations of the 并了解
players and so forth can help us quite 玩家等可以帮助我们
but so when we think about this a cartel 但是当我们考虑这个卡特尔时
is much like a repeated prisoner's 就像是一个反复犯人的
dilemma and in order to make sure that 困境，并确保
other people behave if you want to get 如果你想得到别人的行为
people abiding by this you need to be 遵守这一点的人，你需要
able to observe other people's play and 能够观察其他人的游戏
react quickly to that and punish them 对此迅速做出反应并惩罚他们
desired behavior so if you form a cartel 期望的行为，所以如果您形成卡特尔
and so everybody here's our quotas don't 所以每个人都是我们的配额
pump more than this you be able to need 泵出更多您需要的
to be able to respond to somebody who 能够回应某人
ends up breaking their agreement and 最终违反了他们的协议，
pumping too much so you need to be able 抽太多，所以你需要能够
to observe what's going on you also need 观察正在发生的事情，您还需要
to care about the future right so if you 关心未来的权利，如果你
stop caring about the future and only 不要只关心未来
care about today then it's very tempting 在乎今天，这很诱人
from one of these countries just to say 来自这些国家之一
okay forget the agreement I'm just 好吧，忘了我只是达成的协议
pumping as much as I can today the price 我今天能抽得最多
is very high I'm going to grab what I 很高我要抓住我的东西
can and war certainly didn't help this 可以，战争当然没有帮助
right so if you have a war you need cash 对，所以如果你有战争需要现金
upfront you're going to want to pump 前期，你要抽水
much more oil and that makes it much 更多的石油，这使它变得更多
more difficult to abide by the cartel 更难以遵守卡特尔
agreement you also need a stable set of 同意你还需要一套稳定的
players and and stationarity so the more 玩家和平稳性
complicated the setting becomes and the 设置变得复杂，并且
more sources of oil there are in the 有更多的石油来源
world and so forth so constantly 世界等等不断
changing sources of production can hurt 改变生产来源可能会伤害
growing demand can help actually right 需求的增长可以帮助实际上正确
so if the world is getting more and more 所以如果世界越来越多
oil dependent and countries come online 石油依赖国家上线
that have more and more demand for oil 对石油的需求越来越大
that can help drive the price up so in 可以帮助推动价格上涨
understanding repeated games we'll have 了解我们将要玩的重复游戏
to account for a lot of things over time 随着时间的流逝要占很多东西
but we can begin to analyze this using 但是我们可以开始使用
the tools of game theory and looking at 博弈论和观察工具
situations where people are playing 人们在玩的情况
games but they're playing them over and 游戏，但他们正在玩这些游戏，
over and over again and trying to 一遍又一遍，试图
understand the consequences of that 了解其后果
how does threats of future play impact 未来的威胁如何产生影响
play today so that's the basic idea and 今天玩，这是基本思路，
let's get into that in a little bit more 让我们多谈一点
detail 详情