What ⊦ means
It marks a judgment as asserted. The formula that follows is presented as true; the sign alone does not prove it.
Frege’s assertion sign first appeared in Begriffsschrift in 1879. Its horizontal stroke introduced content; the upright marked the act of judging it.
Later turnstile marks distinguish proof from semantic consequence.
Specialist notation for formal logic.
Check the system’s definitions before swapping it with ⊢ or ⊨.
Don't confuse it with
2Questions people ask
1Why 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 22A6, 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 “assertion”.
Linux
Ctrl+Shift+UType 22a6, then Enter or Space.
HTML
⊦CSS
\22A6Unicode input
Enter U+22A6 through your operating system’s Unicode hex input, if enabled.
LaTeX (STIX Two)
Load `stix2`; use `\assert` in math mode.
Codes and encoding1 code points
HTML decimal
⊦
HTML hex
⊦
CSS content
content: "\22A6";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%8A%A6
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.