Comment on 1 + 1

• FiskFisk33@startrek.website ⁨1⁩ ⁨year⁩ ago

  Image

  I love the comment that it’s “occasionally useful”

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  • Wilzax@lemmy.world ⁨1⁩ ⁨year⁩ ago

    Hmm yes… set theory… I don’t understand anything happening here

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    • FiskFisk33@startrek.website ⁨1⁩ ⁨year⁩ ago

      There is actually a really good explanation for us curious non-mathematicians here:
      blog.plover.com/math/PM.html

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      • MaliciousKebab@sh.itjust.works ⁨1⁩ ⁨year⁩ ago

        That’s some good read, thank you so much.

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• MBM@lemmings.world ⁨1⁩ ⁨year⁩ ago

  + is a map from N×N to N where a + 0 = a and a + S(b) = S(a + b) (S is the successor function that gives the next number).
  Then 1 + 1 = 1 + S(0) = S(1 + 0) = S(1) = 2.

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  • funkless_eck@sh.itjust.works ⁨1⁩ ⁨year⁩ ago

    seems a little sus to use + to define +

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    • apolo399@lemmy.world ⁨1⁩ ⁨year⁩ ago

      No, it’s correct. You define the operation by it’s properties. It’s not saying that “a plus 0 = a” but "the result of applying the binary operation ‘+’ to any number with 0 should give the original number."

      • is just a symbol. You could instead write it as +(a,0)=a and +(a,S(b))=S(+(a,b)).

      You have to have previously defined 1=S(0), 2=S(1), 3=S(2), and so on.

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