其他
TED演讲：为什么“麦当劳”旁一般会有一个“肯德基”？
为什么所有加油站，咖啡馆和餐馆都集中在一个拥挤的地方？就好像你会经常发现，一条街上，一个麦当劳旁边必定有一个肯德基。这只是一个偶然的现象吗？
时长：3:55
为什么加油站总是建在其他加油站旁边？
Why can I drive for a mile without finding a coffee shop, and then stumble across three on the same corner?为什么我们有时候会开了一英里却找不到却找不到一家咖啡店，然后突然发现有三家咖啡店在同一拐角？
Why do grocery stores, auto repair shops and restaurants always seem to exist in groups, instead of being spread evenly throughout a community?为什么杂货店，汽车修理店和餐厅总是聚在一起？而不是均匀地分布在整个区域？
While there are several factors that might go into deciding where to place your business, clusters of similar companies can be explained by a very simple story called Hotelling's Model of Spatial Competition.虽然有多种因素可能会决定在哪儿开店，但是我们可以用一个简单的故事来解释为什么同类商店都聚集在一起，这就是我们所说的霍特林模型空间竞争。
Imagine that you sell ice cream at the beach. Your beach is one mile long and you have no competition. Where would you place your cart in order to sell the most product?想象一下你在海滩上卖冰淇淋。海滩长达一英里并且你没有任何竞争者。你会把你的冰淇淋车放在哪里以卖出最多的产品？
In the middle. The one-half-mile walk may be too far for some people at each end of the beach, but your cart serves as many people as possible.在海滩中间。对于在海滩两端的某些人来说，他们最多只用走半英里，但是你的冰淇淋车现在可以卖出最多的冰淇淋。
One day you show up at work just as your cousin Teddy is arriving at the beach with his own ice cream cart. In fact, he's selling exactly the same type of ice cream as you are.有一天你又来海滩卖冰淇淋，发现你的表兄弟Teddy带着他的冰淇淋车也在卖冰淇淋。并且，他卖的冰淇淋和你的一模一样。
You agree that you will split the beach in half. In order to ensure that customers don't have to walk too far, you set up your cart a quarter mile south of the beach center, right in the middle of your territory.为了让客户走的路程更短一些，你同意和他平分海滩。你把你的车放在距离海滩最南端的1/4的地方，就在你的地盘的中央。
Teddy sets up a quarter mile north of the center, in the middle of Teddy territory. With this agreement, everyone south of you buys ice cream from you. Everyone north of Teddy buys from him, and the 50% of beachgoers in between walk to the closest cart.Teddy把它的冰淇淋车放在距离海滩北端1/4的地方，这是Teddy地盘的中央。有了这个协议，在海滩南边这些人都会来你这里买冰淇淋。在北边的那些人会从Teddy那里买冰淇淋。顾客都会去最近的冰淇淋车那里买。
No one walks more than a quarter of a mile, and both vendors sell to half of the beachgoers.没有人会走1/4英里以上的路程。你们各自供应所有顾客所需冰淇淋的一半。
Game theorists consider this a socially optimal solution. It minimizes the maximum number of steps any visitor must take in order to reach an ice cream cart.博弈论认为这是一个社会最优的解决方案。它把顾客为了走到冰淇淋车所需的最长路程给缩小了，
The next day, when you arrive at work, Teddy has set up his cart in the middle of the beach. You return to your location a quarter mile south of center, and get the 25% of customers to the south of you.第二天，你刚开始卖冰淇淋的时候，发现Teddy把他的冰淇淋车放在了海滩的中间。你回到了海滩南端的中间，并且只得到了25%的顾客。
Teddy still gets all of the customers north in Teddy territory, but now you split the 25% of people in between the two carts.Teddy仍然获得了他原先在海滩南端的顾客，但现在有25%的顾客处于两部冰淇淋车的中间。
Day three of the ice cream wars, you get to the beach early, and set up right in the center of Teddy territory, assuming you'll serve the 75% of beachgoers to your south, leaving your cousin to sell to the 25% of customers to the north.在‘冰淇淋战争’的第三天，你更早的来到了海滩，并把你的冰淇淋车放在了Teddy地盘的中间，假设你可以服务在你南边的75%的海滩行人，剩下你的表兄弟服务25%的顾客。
When Teddy arrives, he sets up just south of you stealing all of the southerly customers, and leaving you with a small group of people to the north.当Teddy来的时候他把车放在了你的南边。偷走了原本属于你的所有的南边的客户，并且只给你留了很少一点的在北边的顾客。
Not to be outdone, you move 10 paces south of Teddy to regain your customers. When you take a mid-day break, Teddy shuffles 10 paces south of you, and again, steals back all the customers to the far end of the beach.为了不被淘汰，你移到了Teddy南边的10步远以重新获得你的顾客。在你中午休息的时候，Teddy又移到了你南边的10步远的地方，再次获得了直到最南边的所有顾客。
Throughout the course of the day, both of you continue to periodically move south towards the bulk of the ice cream buyers, until both of you eventually end up at the center of the beach, back to back, each serving 50% of the ice-cream-hungry beachgoers.在这一天里，你们不停的移动到对方的南边以获得南边的冰淇淋买家，直到你们最终都到达了海滩的中间，背对背，各自服务50%的冰淇淋买家。
At this point, you and your competitive cousin have reached what game theorists call a Nash Equilibrium, the point where neither of you can improve your position by deviating from your current strategy.在这一点上，你和你的表兄弟达到了博弈论中所谓的纳什均衡。你无法通过移动你的位置以获得更高的收益。
Your original strategy, where you were each a quarter mile from the middle of the beach, didn't last, because it wasn't a Nash Equilibrium. Either of you could move your cart towards the other to sell more ice cream.你原计划是俩人都在海滩的1/4的位置来平分顾客，好景不长，因为它不是一个纳什均衡。你们各自都可以移动位置以卖出更多的冰淇淋。
With both of you now in the center of the beach, you can't reposition your cart closer to your furthest customers without making your current customers worse off.现在你们俩都处于海滩的中间，你无法移动位置来节省最远的顾客要走的路程而不使得你的当前客户需要走的路程加长。
However, you no longer have a socially optimal solution, since customers at either end of the beach, have to walk further than necessary to get a sweet treat.但是，您不再有社会最优的解决方案，因为顾客在海滩的两端，为了获得‘甜蜜的享受’他们必需走那么远。
Think about all the fast food chains, clothing boutiques, or mobile phone kiosks at the mall. Customers may be better served by distributing services throughout a community, but this leaves businesses vulnerable to aggressive competition.想想所有的快餐连锁店，服装精品店，或者在商场的移动电话亭。也许当他们平均分布的时候顾客可能会获得更好的服务，但是这使企业受到激烈的竞争。
In the real world, customers come from more than one direction, and businesses are free to compete with marketing strategies, by differentiating their product line, and with price cuts, but at the heart of their strategy, companies like to keep their competition as close as possible.在现实世界中，客户来自四面八方，并且企业之间用营销策略自由竞争，通过推出不同的产品，降价，但关键是企业要保持自己的竞争力。
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