ELI5: Explain Like I'm 5

Young tableau

Have you ever played a game where you have to arrange some numbers in a specific way? That's kind of what a young tableau is. It's like a puzzle board made up of numbers where we have to arrange them in a specific order.

Let's think of a very simple example. Suppose we have three boxes, and we need to fill them up with some numbers. We want to make sure that the smallest number goes in the first box, the second-smallest number goes in the second box, and the largest number goes in the third box. In this case, we have to use a Young tableau to show the arrangement.

A Young tableau is like a grid, with some boxes where we can put numbers. Each row and column of the tableau has to be sorted in a specific order. For example, the first row should have the smallest number, the second row should have the second-smallest number, and so on. Similarly, the first column should also have the smallest number at the top, the second-smallest number in the next box, and so on.

Now, to fill up our three boxes with numbers, we can use the Young tableau we just made. We start by putting the smallest number in the first box. Then we put the second-smallest number in the second box. Since the second row is empty, we can put the number there. If there was a number in the second row already, we would compare the number we're trying to place with the number in that box to see which one is smaller. We'd put the smaller number in that box and the other one in the next available box.

We repeat this process until we fill up all three boxes. And voila! We have made a Young tableau.

Young tableaus are actually used a lot in computer science to solve different problems, like sorting algorithms. They're very useful because they can help us arrange numbers in a specific order in a very efficient way.
Related topics others have asked about: