Beth number

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In mathematics, particularly in set theory, the beth numbers form a certain (unset) sequence of infinite cardinal numbers (also known as transfinite numbers), conventionally written ℶ0,ℶ1,ℶ2,ℶ3,…, where ℶ is the Hebrew letter beth. The beth numbers are related to the aleph numbers (ℵ0,ℵ1,…), but unless the generalized continuum hypothesis is true, there are numbers indexed by ℵ that are not indexed by ℶ. On the other hand, beth numbers are cofinal (every cardinal number is less than a beth number) in plain Zermelo-Fraenkel set theory.

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