【TED】为什么竞争者要把店开在彼此旁边？
为什么加油站总是建在其他加油站旁边？为什么我们有时候会开了一英里却找不到一家咖啡店？然后突然发现有3家咖啡店在同一个拐角？为什么杂货店，汽车修理店和餐厅似乎总是聚在一起，而不是均匀地分布在整个区域？这些看起来奇怪的分布，其实有一个简单的原因——霍特林模型空间竞争。
Why are gas stations always built right next to other gas stations?
为什么加油站总是建在其他加油站旁边？
Why is that 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一家咖啡店？然后突然发现有3家咖啡店在同一个拐角？
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，汽车修理店和餐厅似乎总是聚在一起，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里开店，但可以用一个简单的故事来解释为什么同类商店都聚在一起，这被称为霍特林模型空间竞争。
Imagine that you sell ice cream at the beach.
想象一下你在海滩上卖冰淇淋。
Your beach is one mile long and you have no competition.
海滩长达一英里并且没有任何竞争者。
Where would you place your cart in order to sell the most product?
你会把你的冰淇淋车放在哪里以卖出最多的产品？
In the middle.
在海滩中间。
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.
对于在海滩两端的某些人来说，他们最多只用走半英里，但你的冰淇淋车却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.
有一天你又来海滩卖冰淇淋，发现你的表兄弟泰迪带着他的冰淇淋车也在卖冰淇淋。
In fact, he's selling exactly the same type of ice cream as you are.
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1/4的地方，就在你地盘的中央。
Teddy sets up a quarter mile north of the center, in the middle of Teddy territory.
泰迪把它的冰淇淋车放在距离海滩北端1/4的地方，这是泰迪地盘的中央。
With this agreement, everyone south of you buys ice cream from you.
有了这个协议，在海滩南边这些人都会来你这里买冰淇淋。
Everyone north of Teddy buys from him, and the 50% of beachgoers in between walk to the closest cart.
在北边的那些人会从泰迪那里买冰淇淋。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.
博弈论认为这是一个社会最优的解决方案。
It minimizes the maximum number of steps any visitor must take in order to reach an ice cream cart.
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.
第二天你刚开始卖冰淇淋的时候发现泰迪把他的冰淇淋车放在了海滩的中间。
You return to your location a quarter mile south of center and get the 25% of customers to the south of you.
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.
泰迪仍然获得了他原先在海滩北端的顾客，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泰迪地盘的中间，假设你可以服务在你南边75%的海滩行人，留给你表兄弟服务北边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.
当泰迪来的时候，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儿的在北边的顾客
Not to be outdone, you move 10 paces south of Teddy to regain your customers.
为了不被淘汰，你移到了泰迪南边10步远的地方以重新获得你的顾客
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.
在你中午休息的时候，泰迪又移到了你南边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.
你原计划是俩人都在海滩1/4的位置来平分顾客，但好景不长，因为它不是一个纳什均衡。
Either of you could move your cart towards the other to sell more ice cream.
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，而且也不能使你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，为了获得甜蜜享受的他们必需走那么远。
Think about all the fast food chains, clothing boutiques, or mobile phone kiosks at the mall.
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。
Customers may be better served by distributing services throughout a community, but this leaves businesses vulnerable to aggressive competition.
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.