ELI5: Explain Like I'm 5

Representation theory of the symmetric group

Okay kiddo, let's imagine you have a group of friends who like to play games together. Sometimes you play tag, sometimes you play hide and seek, and sometimes you play rock-paper-scissors.

Now, just like how you have friends with different personalities and talents, some games may require different skills from each friend. For example, in tag, you may need a fast friend who can run quickly to catch others. In hide and seek, you may need a friend who is very good at hiding and being quiet. And in rock-paper-scissors, you need to be smart and quick to choose your strategy.

This is kind of like how the symmetric group works. The symmetric group is made up of all the possible ways you can arrange a certain number of objects, like arranging a deck of cards. Each way you can arrange the objects is called a permutation. Just like how you need different skills for different games, the different permutations in the symmetric group have their own unique attributes and properties.

Representation theory is like trying to understand what happens when you take these attributes and properties and represent them in a different way. It's like trying to translate the game of tag from English to French - even though the words are different, the ideas are still the same.

So, in summary, representation theory of the symmetric group is like trying to understand the different ways you can arrange a certain number of objects, and how those arrangements have unique attributes and properties that can be translated into a different language or representation.