`integer` -
The sentence `(integer )` means that the object denoted by
is an integer.

`real-number` -
The sentence `(real-number )` means that the object denoted by
is a real number.

`complex-number` -
The sentence `(complex-number )` means that the object denoted by
is a complex number.

`(defrelation number (?x) :=`

` (or (real-number ?x) (complex-number ?x)))`

`(defrelation natural (?x) := (and (integer ?x) (>= ?x 0)))`

`(defrelation rational-number (?x) :=`

` (exists (?y) (and (integer ?y) (integer (* ?x ?y)))))`

`<` -
The sentence `(< )` is true if and only if the number denoted by
is less than the number denoted by .

`(defrelation > (?x ?y) := (< ?y ?x))`

`(defrelation =< (?x ?y) := (or (= ?x ?y) (< ?x ?y)))`

`(defrelation >= (?x ?y) := (or (> ?x ?y) (= ?x ?y)))`

`(defrelation positive (?x) := (> ?x 0))`

`(defrelation negative (?x) := (< ?x 0))`

`(defrelation zero (?x) := (= ?x 0))`

`(defrelation odd-integer (?x) := (integer (/ (+ ?x 1) 2))`

`(defrelation even-integer (?x) := (integer (/ ?x 2))`

`logbit` -
The sentence `(logbit )` is true if bit
of is 1.

`logtest` -
The sentence `(logtest )` is true if the logical
*and* of the two's-complement representation of the integers
and is not zero.

Wed Dec 7 13:23:42 PST 1994