Liu Jian, Beijing Technology and Business University
In recent thirty or forty years, economics has experienced a "game theory revolution", that is, introducing the concepts and methods of game theory to transform the thinking of economics and promote the research of economics. Awarding the Nobel Prize in Economics to three game theory experts, including Dr. Nash of Princeton University, can be regarded as a sign, which naturally stimulates people's enthusiasm for understanding game theory. As the frontier field of modern economics, game theory has become the mainstream basic analysis tool.
Game theory is to study the direct interaction between the behaviors of decision-making subjects, that is, the choice of one subject is influenced by the choice of other subjects, which in turn affects the decision-making and equilibrium of other subjects.
In terms of price
If several stores unite.
You can naturally sell more expensive things.
But as long as one of them reduces the price
Guests from other stores will go to that one.
Then several other companies will also be forced to cut prices.
Store association is the best way to make money.
But the relationship between shops is generally hostile.
In case someone orders a low price to lure away the guests.
All the shops will keep the price as low as possible.
In economics, "pig's income" is a famous game theory example.
This example is about: there are two pigs, a big pig and a little pig in the pigsty. There is a pedal on one side of the pigsty. Every time you step on the pedal, a small amount of food will fall on the feeding port on the other side of the pigsty far from the pedal. If one pig steps on the pedal, another pig has a chance to eat the food that has fallen on the other side first. As soon as the pig steps on the pedal, the big pig will eat all the food just before the pig runs to the trough; If the big pig steps on the pedal, there is still a chance for the little pig to run to the trough and compete for the other half before eating the fallen food.
So, what strategy will the two pigs adopt? The answer is: Piglets will choose the "hitchhiking" strategy, that is, they will wait comfortably in the trough; The big pig ran tirelessly between the pedal and the trough, just for a little leftovers.
What is the reason? Because, little pigs can get nothing by pedaling, but they can eat food without pedaling. For piglets, it is always a good choice not to step on the pedal whether the big pig does or not. On the other hand, the big pig knows that the little pig can't step on the gas pedal. It's better to step on the accelerator by himself than not to step at all, so he has to do it himself.
The phenomenon of "the little pig is lying down and the big pig is running" is caused by the rules of the game in the story. The core indicators of the rules are: the number of things falling each time and the distance from the pedal to the feeding port.
If we change the core indicators, will there be the same scene of "pigs lying down and big pigs running" in the pigsty? Give it a try.
Change scheme 1: reduction scheme. Feeding is only half of the original weight. As a result, neither the little pig nor the big pig kicked. The little pig will step on it, and the big pig will finish the food; If the big pig steps on it, the little pig will finish the food, too. Whoever pushes means contributing food to each other, so no one will have the motivation to push.
If the goal is to make pigs pedal more, the design of this game rule is obviously a failure.
Variation scheme 2: Incremental scheme. Feed twice as much as before. As a result, both the little pig and the big pig can pedal. Anyone who wants to eat will kick. Anyway, the other party won't eat all the food at once. Piglets and big pigs are equivalent to living in a materialistic society with relatively rich materials, and their sense of competition is not very strong.
For the designer of the rules of the game, the cost of this rule is quite high (providing two meals at a time); Moreover, because the competition is not strong, it has no effect to let the pigs push more.
Variant 3: Decreasing plus shifting scheme. Feed only half the original weight, but at the same time move the feeding port near the pedal. As a result, both the little pig and the big pig pushed hard. Those who wait will not eat, and those who work hard will get more. Every harvest is just a flower.
Benwoju
Ross and Rachel are a couple, and they have been having an affair in secret. But they don't want to be apart, but want to live together, so they have to face a question: should they confess their infidelity to each other? For Ross, he has two strategies, "confession" or "concealment". If he confesses his fault to Rachel, Rachel, as an "innocent" party (Ross doesn't know about Rachel's affair, and Rachel chooses to "hide"), will occupy a psychological advantage in the relationship between the two, thus leaving Ross in a weak state. If he decides to hide it, he will be condemned by his conscience. This game is symmetrical, so Rachel has the same dilemma.
We introduce the income concept of economics to measure the advantages and disadvantages of strategies in the game, and the upper limit of income is set at 10 points. If Rachel chooses "hide" and Ross chooses "confess", Rachel will occupy the psychological advantage of "I am innocent" and get 9 benefits, while Ross on the inferior side will only get 5 benefits. The reverse is also true for Ross. If two people choose to "confess" in unison, they will feel the pain of betrayal, but they can forgive each other, and their gain is 8. If two people choose "hiding", the foundation of trust that feelings can maintain has actually disappeared, which is a great loss for both sides, and the gain is only 6. The following table lists the benefits of both parties in four cases, and Rachel ranks first.