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
