ELI5: Explain Like I'm 5

Category of preordered sets

Okay kiddo, so imagine you have a group of toys. However, these toys are special because they come with a set of rules on how you can play with them. These rules say what order you have to play with the toys in and what toys can be played with at the same time.

A category of preordered sets is kind of like that. It's a group of things (called sets) that come with rules on how you can relate them to each other. These rules are called orders, which tell you how to arrange the elements in each set from smallest to biggest or biggest to smallest.

For example, let's say we have a set of numbers: {2, 7, 9}. We can put them in order from smallest to biggest: {2 < 7 < 9}. We can also put them in order from biggest to smallest: {9 > 7 > 2}. Both of these orders are called preorders, and they tell us how the elements are related to each other.

So, a category of preordered sets is a group of these ordered sets that follow certain rules. For instance, all the sets in the category might have to be ordered in the same way. Or, they might have to have a specific relationship with each other (like the way addition and subtraction are related).

Just like with the toys, these rules help us understand how things relate to each other and can be used to solve problems or discover new things.
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