Description: Extend class notation to
include unary minus. The symbol 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 ( ) and subtraction
cmin 8130 ( ) to prevent syntax ambiguity. For example, looking at the
syntax definition co 5877, if we used the same symbol
then "  " could
mean either "
" minus
" ", or
it could represent the (meaningless) operation of
classes "
" and "
" connected with
"operation" " ".
On the other hand, "  
" is unambiguous. |