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[–] Miller@lemmy.world 2 points 4 months ago (8 children)

My old statistics lecturer would write x-¹ as shorthand meaning everything that is not x, I thought it was in more common usage but perhaps not. I know it more generally means the reciprocal, he just expected you to know which he meant by context.

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[–] nyan@lemmy.cafe 7 points 4 months ago (6 children)

x-¹

Where I come from, that's read as "x to the [power of] minus one". "x minus one" is, well, x - 1. Not the same thing at all.

(I admit, my chances of deciphering what you meant might not have been all that high even if you'd used the correct phrasing, but without it, the chance was zero.)

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[–] Miller@lemmy.world -4 points 4 months ago* (last edited 4 months ago) (5 children)

It was a shorthand he used, he wrote it as a superscript, it must of been his own, it was useful in terms of statistics analysis.

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[–] SCmSTR@lemmy.blahaj.zone 7 points 4 months ago (2 children)

It has been a LONG time since I did any real math and never took statistics, but wouldn't x^(-1) just be 1/(x)? I don't know if that equates to "everything that isn't x". I feel like there's a specific way to write that, but a negative exponent is not that, I don't think, but also I have no idea.

I looked it up. Looks like this stuff is maybe from set theory? Which I sooorrrrt of remember doing at some point?

My best guess is your professor either said something from this, or you misremembered, or I'm totally off base and I'm still curious.

https://en.wikipedia.org/wiki/Complement_(set_theory)

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[–] Miller@lemmy.world 1 point 4 months ago (1 child)

Your best guess is reasonable, I may have misremembered, it could have been A' spoken as A dash and meaning the complement and I hallucinated the negative but I think I recall some noted confusion with the reciprocal x-¹ = 1/x.

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[–] aloofPenguin@lemmy.world 2 points 4 months ago

Yeah, to me, A' checks out since that would mean NOT A which I believe was what you were getting at.