(subclass NonnegativeRealNumber RealNumber) | Merge.kif 1921-1921 | Nonnegative real number is a subclass of real number |
(subclass PositiveRealNumber NonnegativeRealNumber) | Merge.kif 1932-1932 | Positive real number is a subclass of nonnegative real number |
(subclass NonnegativeInteger NonnegativeRealNumber) | Merge.kif 1976-1976 | Nonnegative integer is a subclass of nonnegative real number |