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ℶ

bet symbol

Bet Symbol

54/78

In set theory, ℶ names beth numbers: labels for infinite set sizes. Each successor stage takes the size of all subsets of the previous stage’s set. A subscript, as in ℶ₀ or ℶ₁, marks the stage. The notation borrows the form and name of Hebrew bet, but is a separate mathematical character.

Text symbol

What ℶ means

It labels beth numbers in a hierarchy of infinite sizes.

The beth hierarchy begins with a base size. At each successor stage—the step immediately after another stage—it takes the size of the previous set’s power set, or all its subsets. This tracks one way infinite sizes grow, alongside the aleph hierarchy, which orders infinite cardinalities.

The earliest credited use of beth notation is in Charles Sanders Peirce’s letter to Georg Cantor in December 1900. The notation seems to have fallen out of use, then was back in mathematical use by the 1950s.

Is ℶ the Hebrew letter ב?

No. ℶ is mathematical notation; ב is a Hebrew letter.

ℶ borrows the name and shape of Hebrew bet, but it serves a mathematical purpose. Formulas use ℶ as a left-to-right symbol; ב belongs in right-to-left Hebrew writing.

Formal and specialist: it signals set theory, logic, or advanced mathematical writing.

Using it as Hebrew text can change both the character and the text direction.

Part of the collection

What it means when someone sends it to you

4 readings

The starting cardinal in the beth hierarchy.

Don't confuse it with

1

Combination ideas

4
Beth zero: equals ℵ₀, the size of the natural numbers.
Beth one: the size of the real numbers, the continuum.
Beth two: the number of all sets of real numbers.
The continuum hypothesis: the first uncountable size equals the continuum.

Questions people ask

1

Does ℶ₁ always equal ℵ₁?

No. ℶ₁ is the size of the real numbers. It equals ℵ₁ only under the continuum hypothesis, which says no infinite size lies between countable infinity and the real numbers.

How to type or find ℶ

Also called
beth · beth number · beth notation
Search it as
set theory · power set · infinite cardinal · cardinality · aleph beth · beth LaTeX
Shows up in
Anything that takes text · its shape is whatever your font draws
Windows (Word)
⎇Alt+XType 2136, then AltX to get ℶ.
Windows
⊞Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win .).
macOS
⌃Control+⌘Command+␣SpaceOpen the character viewer and search “bet symbol”.
Linux
⎈Ctrl+⇧Shift+UType 2136, then Enter or Space.
HTML
ℶ
CSS
\2136
LaTeX
In a LaTeX math environment with unicode-math, type \beth; its symbol table maps the command to ℶ.
Codes and encoding1 code points
HTML decimal
ℶ
HTML hex
ℶ
CSS content
content: "\2136";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%84%B6
1
On screen
1
Code points
1
JS .length
3
UTF-8 bytes

A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.

Families this belongs to

2

Typography & punctuation332 symbols

Letters1,265 symbols