• Ephera
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    125 months ago

    > natural numbers
    > rational numbers
    > real numbers
    > regular numbers
    > normal numbers
    > simply normal numbers
    > absolutely normal numbers

    Have mathematicians considered talking about what numbers they find okay, rather than everyone just picking their favorite and saying that one’s the ordinary one?

    • @[email protected]
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      5 months ago

      I mean, unironically yes. It seems the most popular stance is that all math regardless of how weird is Platonically real, although that causes some real bad problems when put down rigorously. Personally I’m more of an Aristotelian.

      In the case of things like rational or real numbers, they have a counterpart that’s weirder (irrational and imaginary numbers). For the rest I’m not sure, but it’s pretty common to just pick an adjective for a new concept. There’s even situations where the same term gets used more than once in different subfields, and then they collide so you have to add another one to clarify.

      For example, one open interval in the context of a small set of open intervals isn’t closed analytically under limits, or algebraically closed, but is topologically closed (and also topologically open, as the name suggests).