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Minimax

math Maturity 7-9 Next article →

Imagine you are playing a game against a friend. You want to win, but you also want to be safe. Minimax is a special rule used to make smart choices. It helps you pick a move that keeps your loss small. This is very helpful when you face a worst-case scenario. A worst-case scenario is the worst thing that could happen to you.

Minimax
Minimax

This idea is used in many areas like artificial intelligence and philosophy. It is also part of decision theory and statistics. It helps people and computers make plans when they are not sure what will happen next.

To understand how it works, think about a player trying to stay safe. This is called the maximin approach. First, you look at every move you could possibly make. For each move, you imagine the other players do their worst to you. You find the smallest value you would get for each of your choices. Then, you pick the choice that makes that smallest value as high as possible.

Plminmax
Plminmax

This way, you maximize your minimum gain. You are choosing the best of the worst outcomes.

There is another way to look at this called minimax. This version is slightly different because the order of thinking changes. In minimax, you look at what the other players might do first. You imagine you know their moves, and then you pick your best response. This puts you in a much better position than the maximin way.

The minimax value is the smallest value that others can force you to receive. It is the largest value you can get if you know their actions. The maximin value will always be less than or equal to the minimax value.

We can see this with a real example using numbers. Imagine a row player who can choose moves labeled T, M, or B. A column player can choose moves L or R. If the row player chooses T, they are guaranteed at least 2 points. If they choose M, they might get as little as -10. If they choose B, they could lose 100 points.

By using the maximin rule, the row player picks T to stay safe. This gives them a guaranteed value of 2. The column player also looks for their own safe choice.

These ideas started with studying zero-sum games. A zero-sum game is one where players take turns or move at the same time. The rules have since grown to cover much more complex games. They also help with general decision-making when there is a lot of uncertainty. Scientists use these math tools to help computers play games against humans. It turns a scary unknown future into a plan you can follow. Even in a world of chance, these rules help find a steady path.

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