On Fri, Sep 18, 2015 at 1:12 PM, Random832 <random...@fastmail.com> wrote: > On Fri, Sep 18, 2015, at 14:24, Terry Reedy wrote: >> The semantics Python copies from math is "a op b op c == a op b and b op >> c", > > I don't believe those *are* the semantics in math. I believe that in > math this notation is *specifically* meant to support "all of these > things are related to all of the others in ways that can be summarized > in a single expression" and that mixing operations in a way that does > not allow that is a misuse of the notation. In other words, any "a op b > op c" that does not allow you to make a statement on how a is related to > c is a *mistake*, because it means that you're welding together two > things that aren't logically connected to each other at all. > > If there is no operator op3 where a op1 b op2 c implies a op3 c, then > you should not put a and c in the same inequality, full stop.
Whoever wrote the Wikipedia article disagrees: https://en.wikipedia.org/wiki/Inequality_(mathematics)#Chained_notation Although the reference to Python leads one to suspect that this could be based more on Python's semantics than on actual mathematics. -- https://mail.python.org/mailman/listinfo/python-list
