greg wrote:
Terry Reedy wrote:
In Math and Python, a<b<c means a<b and b<c, not (a<b)<c or a<(b<c).
!= is a comparison operator like <,
Although Python extends the chaining principle to
!=, this is somewhat questionable, because
a < b and b < c implies a < c, but a != b and
b != c does not imply a != c.
I'm not sure I've ever seen a mathematician
write a != b != c, but if I did, I would tend
to think he meant to say that none of a, b,
c are equal to any other. That's not what it
means in Python, though.
However, == is transitive, and a == b == c is quite common.
It would hardly do to have different rules for !=.
Either we have a uniform rule for a compare_op b compare_ob c, as we do,
or we have several fussy rules that would be hard to remember.
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