Description: Extend class notation to include unary minus. The symbol -u is not a class by itself but part of a compound class definition. We do this rather than making it a formal function since it is so commonly used. Note: We use different symbols for unary minus ( -u ) and subtraction cmin ( - ) to prevent syntax ambiguity. For example, looking at the syntax definition co , if we used the same symbol then " ( - A - B ) " could mean either " - A " minus " B ", or it could represent the (meaningless) operation of classes " - " and " - B " connected with "operation" " A ". On the other hand, " ( -u A - B ) " is unambiguous.
| Ref | Expression | ||
|---|---|---|---|
| Assertion | cneg | class - 𝐴 |