4 ms·

> ℵ₀ is equal to ℶ₀ That's the definition of ℶ₀. So of course they are equal. "Two" is also just a name for the successor of 1. I could also call it "bob" and

> ℵ₀ is equal to ℶ₀ That's the definition of ℶ₀. So of course they are equal. "Two" is also just a name for the successor of 1. I could also call it "bob" and thus "two" would not be unique, but I don't see the point. The fact is that the cardinal of countable numbers is a mathematical concept which has a name, and can be manipulated. Which is what matters, and what the parent poster maybe did not understand.

thaumasiotes 4y ago
> "Two" is also just a name for the successor of 1. I could also call it "bob" and thus "two" would not be unique, but I don't see the point. There is no point, because 2 is well defined. That is also true of the ℶ numbers, but it is not true of the ℵ numbers. That's why, in that case, it's necessary to have multiple names for the same number. > The fact is that the cardinal of countable numbers is a mathematical concept which has a name, and can be manipulated. No, that's not a fact, that's what I'm saying. The cardinality of the naturals is a mathematical concept. It is referred to as "the cardinality of the naturals", or by many similar phrases. But it is not referred to by the name ℵ₀. ℵ₀ is a name that refers to a different concept, the cardinality of the ordinal number ω. The two cardinalities are equal, but ℵ₀ specifically refers to one of them, conceptually, rather than the other. ℶ₀ refers to a different concept again. That's the one that is meant to be manipulable.