On 27/07/2019 17.43, Stefan Ram wrote: > Terry Reedy <tjre...@udel.edu> writes: >> In mathematics, *every* set is 'the'.
This is correct, at least in ZF, where the Axiom of Extensionality says that (in English) if A and B have exactly the same elements, they are the same set. > |Example 2 Let T be an non-empty set and ... > [PDF] Real Analysis on Metric Spaces - Columbia University It's obvious that "an" is a typo, either for "any" or "a". Assume for the sake of argument that it's intended to be "a", as in "Let T be a non-empty set..." T is indeed "a" set, but it's the only set that has the same elements as T. Therefore, once you've let T be some specific non-empty set, it is *the* set T. -- Michael F. Stemper Life's too important to take seriously. -- https://mail.python.org/mailman/listinfo/python-list
