What ⨡ means
It merges two schemas and keeps only the second one's variables. Z notation is a way of describing what a computer system must do using set theory and logic, built up at Oxford University from the late 1970s and used for safety-critical and high-assurance software. Its building block is the schema: a named box listing some variables and the conditions they must satisfy.
Writing S ⨡ T means: take everything S and T require together (as schema conjunction S T would), then hide every variable that is not declared in T. The result still carries S's rules, but from the outside you only see T's names. Specifiers use it to say "this must hold, but only these parts are visible" without listing what to hide one by one.
Part of collections
Don't confuse it with
2
Related characters
2
Worth knowing
- Unicode 3.2 added a batch of Z notation operators in 2002, the same year Z became the international standard ISO/IEC 13568.
Questions people ask
2How is projection different from schema hiding?
Hiding names what to throw away; projection names what to keep, by pointing at a second schema whose variables survive.
Why does ⨡ show as a box?
Your font lacks it. Maths fonts such as Cambria Math or STIX Two include it.
More like this
9
How to type or find ⨡
- Also called
- schema projection · projection operator · Z projection
- Search it as
- Z notation · zproject · \project · Z projection symbol · formal specification symbol
- Shows up in
- Anything that takes text · its shape is whatever your font draws
⨡\2A21\project.Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.