ELI5: Explain Like I'm 5

Isbell conjugacy

Isbell conjugacy is when we have two different ways of dividing things up into groups, but they are actually the same thing.

Imagine you have a bucket of red and blue marbles. You can divide them up by color and put all the red ones in one pile and blue ones in another. Or you could divide them up by size and put all the small ones in one pile and the big ones in another.

Even though you have two different ways of dividing the marbles, they are still the same marbles! This is Isbell conjugacy.

It turns out that Isbell conjugacy is really useful in math because it helps us see how different things can be related to each other, even if they seem really different at first.
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