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Comment by chongli

9 days ago

There's no issue with recursive definitions. That's how arithmetic was original formalized by Peano's axioms [1].

[1] https://en.wikipedia.org/wiki/Peano_axioms

i is also a quaternion. So by this logic we could say complex numbers are made up of quaternions. But we don’t say such things because they wouldn’t be a good mental model of what we want to talk about.

  • > i is also a quaternion

    Yeah, so ?

    The fraction 1/2 is a rational and also a real and also a complex numbers and also a quaternion also an octonion ....

    We use a number along with the minimal abstraction that is sufficient for our purpose.