Treating the abusive unsigned syndrome

[Andrei Alexandrescu]

Kagamin wrote:
> Andrei Alexandrescu Wrote:
> 
>> There are several schools of thought (for the lack of a better
>> phrase):
>> 
>> 1. The Purist Mathematician: We want unsigned to approximate
>> natural numbers, natural numbers aren't closed for subtraction,
>> therefore u1 - u2 should be disallowed.
> 
> I thought, mathematics doesn't distinguish between, say, natural 5,
> integral 5 and real 5. N, Z and R are sets, not types of numbers.
> There is even notion of equivalence class to deem numbers with
> different representation as the same (not just equal).

Right, but the notion of set closedness for an operation comes from math.

Andrei