What ⫳ means
It names the authors’ parallel calculus. They write the system’s name as λ with ⫳ in a small subscript below it. The system connects proofs in linear logic—reasoning about how resources are used—with computer programs that can run in parallel and communicate. Here, the mark names that system; it does not give every equation a parallel-composition rule.
Don't confuse it with
4Questions 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 2AF3, 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 “parallel with tilde operator”.
Linux
Ctrl+Shift+UType 2af3, then Enter or Space.
HTML
⫳CSS
\2AF3MathML 2 source
In MathML 2 markup using its standard symbol entities, write `⫳`.
Codes and encoding1 code points
HTML decimal
⫳
HTML hex
⫳
CSS content
content: "\2AF3";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%AB%B3
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.