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⦰

reversed empty set

Reversed Empty Set

⦰ has no single standard meaning across mathematics, so a formula needs an author-supplied definition. This reversed empty-set symbol belongs to specialist notation and has a documented link to APL's circle-backslash symbol. Its shape alone does not tell you what the writer intends.

Text symbol

Also called: backwards empty set · revemptyset
Search it as: empty set slash · STIX · LaTeX
Shows up in: Anything that takes text · its shape is whatever your font draws

What ⦰ means

Its author must define it; mathematics has no universal reading. Do not treat ⦰ as an automatic substitute for the ordinary empty-set sign ∅; a local notation or a typesetting package may assign it a specific role.

If a formula or specification gives no definition, ask its author before interpreting ⦰.

How do I type ⦰?

Use Unicode hex entry or a supported typesetting command. On Linux, enter hexadecimal 29B0 through your Unicode input method and confirm. In Microsoft Word, type 29B0 and press Alt+X. With STIX in LaTeX, use \revemptyset.

A font without ⦰ may show a missing-character box or a fallback glyph. Check the finished formula in the font where it will appear.

Specialist mathematical and typesetting notation; uncommon in ordinary conversation.

Do not assume ⦰ means the ordinary empty set ∅ without a definition.

Don't confuse it with

∅

Empty Set

∅ is the ordinary empty-set sign. ⦰ is a separate reversed character; do not substitute one for the other unless the notation defines them as equivalent.

Questions people ask

Why does ⦰ show as a box on some devices?

Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.

How to type ⦰

Windows (Word)

Alt+XType 29B0, then Alt+X to get ⦰.

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 “reversed empty set”.

Linux

Ctrl+Shift+UType 29b0, then Enter or Space.

HTML

⦰

CSS

\29B0

Font support

Use a Unicode math font that includes U+29B0; otherwise ⦰ may fall back to another glyph or disappear.

Linux

In a Unicode hex-entry method, enter `29B0` and confirm. The exact shortcut depends on your desktop.

STIX LaTeX

Load STIX and use `\revemptyset` for the reversed empty-set glyph.

Codes and encoding1 code points

HTML decimal

⦰

HTML hex

⦰

CSS content

content: "\29B0";

Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.

URL encoded

%E2%A6%B0

On screen

Code points

JS .length

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

Maths & numbers1,835 symbols

1️⃣📏📐✖️➕➖➗🟰♾️#️⃣*️⃣0️⃣