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 8090 ( ) to prevent syntax ambiguity. For example, looking at the
syntax definition co 5853, 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. |
