Thanks for sharing! I like to look at this example inside the debate of if mathematics are invented or discovered.
> That is how Whitehead and Russell did it in 1910. How would we do it today? A relation between S and T is defined as a subset of S × T and is therefore a set.
> A huge amount of other machinery goes away in 2006, because of the unification of relations and sets.
Relations are a very intuitive thing that I think most people would agree that are not the invention of one person. But the language to describe them and manipulate them mathematically is an invention that can have a dramatic effect on the way they are communicated.
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