The Classic Problem of Game Theory —— Pirates Divide Money

Push forward and backward. If all the robbers from/kloc-0 to 3 feed sharks, only No.4 and No.5 are left, and No.5 will definitely vote against letting No.4 feed sharks and take all the gold coins. Therefore, No.4 can only survive by supporting No.3, and No.3 knows this. The allocation scheme of "100,0,0" will be proposed.

He gave nothing to No.4 and No.5, and kept all the gold coins for himself, because he knew that No.4 got nothing, but he would still vote for it. With his own vote, his plan could be passed.

In the same way. When inferring the scheme of No.3, No.2 will put forward the scheme of "98,0, 1, 1", that is, give up No.3 and give No.4 and No.5 a gold coin each. Since the plan is more favorable to No.4 and No.5 than No.3, they support him and don't want him to be out and assigned by No.3 ... So No.2 took 98 gold coins.

At the same time, the scheme of No.2 will be understood by 1, and a scheme of (97,0, 1, 2,0) or (97,0, 1, 0,2) will be proposed, that is, No.2 will be abandoned, and No.3 will be given a gold coin, and No.4 will be given at the same time. Because the plan of 1 is better for No.3 and No.4 (or No.5) than No.2, they will vote for 1, plus 1, and the plan of 1 will be passed, and 97 gold coins can be easily put in the bag.

answer

Robano. 1 gave 1 gold coin to No.3, 2 to No.4 or No.5, and 97 to myself.

The allocation scheme can be written as (97,0, 1, 2,0) or (97,0, 1, 0,2).

Extended data reasoning process

Reasoning 1:

Suppose ①: 1, No.2 and No.3 have been thrown into the sea, and No.4 will divide the gems.

Infer from the assumption (1):

Conclusion ①: Scheme 4 must be 100 and 0, and it must be passed. (Therefore, No.4 can't be thrown into the sea, which is not inconsistent with the hypothesis (1))

Reasoning ②: (The conclusion of reasoning ① should be used)

Suppose ②: 1 and No.2 have been thrown into the sea, and No.3 will divide the gems.

Infer from conclusion ① and hypothesis ②:

Conclusion ②: No.3 carries out "reasoning ①" reasoning. After getting conclusion ①, I know that I only need to give No.5 0 more gems, that is, the scheme is 99,0, 1, and its scheme will definitely pass. (So No.3 can't be thrown into the sea, which is not contradictory to hypothesis ②, as long as it is not contradictory to hypothesis ② and has nothing to do with hypothesis ①, because they are two independent inferences. )

The rest of the reasoning and so on.

Promote this theme:

X ( 1 =

z(2 = & lt; Z =<x) Pirate's income: When Z is odd, the income is 1, and when Z is even, the income is 0. For X & gt202 hours, it can be discussed under the condition of X=500, and then popularized. Still use the backward method.

Pirate 203 must get 102 votes in favor, but he can't buy it with1kloc-0/associated person 100 gems. So no matter what distribution scheme No.203 proposes, he is destined to be thrown into the sea to feed the fish.

Pirate 204 must get 102 votes in favor. In order to save his life, No.203 must let No.204' s plan pass, so as to avoid No.203 putting forward its own distribution plan. So no matter what scheme No.204 puts forward, it can get the firm support of No.203.

In this way, pirate No.204 can save his life: he can get his own 1 ticket, No.203 1 ticket, and 100 partner bought with 100 gem, which is exactly half the support he needs. The pirate who can get 1 gem from No.204, according to the plan of No.202 Pirate, must belong to No.202 Pirate who got nothing 102.

Pirate 205 must get 103 votes in favor, but he can't buy the support of 102 associates with 100 gems. So no matter what distribution scheme No.205 puts forward, he is destined to be thrown into the sea to feed the fish.

Pirate 206 must get 103 votes in favor. He can get the firm support of No.205, but he can't buy the support of 10 1 00' s associates with the gem of1. So no matter what distribution scheme No.206 proposes, he is destined to be thrown into the sea to feed the fish.

Pirate 207 must get 104 votes in favor. He can get the firm support of 205 and 206, but he can't buy the support of 10 1 00' s associates with the gem of1. So no matter what distribution scheme No.207 proposes, he is destined to be thrown into the sea to feed the fish.

Pirate 208 must get the approval of 104 to get the firm support of No.205, No.206 and No.207, plus its own 1 vote and the bought 100 vote to save its life. The pirates who got the 1 gem on No.208 must belong to those pirates who got the 104. According to Plan No.204, they got nothing.

References:

Baidu Encyclopedia Pirates Divide Money.