A nice, concise overview of the reasons to move away from social media, and how to do it, including the Fediverse and POSSE.

  • TootSweet@lemmy.world
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    6 months ago

    If ℕ is natural numbers and ℚ is rational numbers and ℤ is integers and ℝ is the rational numbers, what are 𝕏 and 𝕐?

    • palordrolap@kbin.social
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      6 months ago

      Not aware of any specific usages, but maybe they’re used as meta-sets. e.g. "consider a set of numbers 𝕏 and a set of numbers 𝕐 … etc, which can’t be done with the defined letters.

      Unicode originally only had the double-struck letters for the defined sets ℂ, ℍ, ℕ, ℙ, ℚ, ℝ and ℤ, but the full alphabets were later added at higher code-points with “reserved” gaps where the defined seven letters would otherwise appear.

      (Complex, Hamiltonian quaternions, Natural, Prime, Quotient (rational), Real and Zahlen, a German word for counting numbers, for anyone wondering.

      Quick edit: Zahl is cognate with English “tell” and “tale” which are both related to “tally”, believe it or not. “Recounting a tale” didn’t used to mean telling(!) a story, but instead literally checking a previous count, and developed the wider sense later.

      Also, ℍ not getting “ℚ” because ℚ couldn’t have “ℝ” is kind of funny.).