On Fri, Sep 11, 2015 at 10:22 PM, Guido van Rossum <gvanros...@gmail.com> wrote:
> I think we're getting into python-ideas territory here... Well, a violation of transitivity of <= in the current CPython implementation may be considered a bug by some. This makes this discussion appropriate for python-dev. We could discuss this on Datetime-SIG, but I think the question is more broad than just datetime. When is it appropriate for Python operators to violate various mathematical identities? We know that some violations are unavoidable when you try to represent real numbers in finite size objects, but when you effectively deal with a subset of integers, what identities are important and what can be ignored for practical reasons? Intuitively, I feel that the hash invariant and the reflexivity and transitivity of == are more important than say distribution law for + and *, but where does it leave the transitivity of <=? Is it as important as == being an equivalence, or it's a nice to have like the distribution law?
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