> What does our theory of databases say about this question? (As opposed to what a psychologist might say about it.)
My understanding is that our theory of databases makes no restriction for a person being their own best friend. In the definition, John wrote:
> Choose any function \\(F(e) : F(x) \to F(y)\\) for each edge \\(e\\) in our graph
So functions that map people to themselves are definitely allowed!
A follow up puzzle:
**Puzzle SL 1**
Is there a finitely presented category which constrains people from being their own best friend?