# successor [*Relation*]

## Purpose

The **successor** relation returns the element which follows a specified member of an ordered set.

## Syntax

**successor** *set member1 member2*

## Domains

The *set* argument is a concept defined as an ordered set.
The *member1* argument is a numeric or symbolic member of *set*.

## Range

The *member2* argument is the numeric or symbolic member which immediately follows *member1* in *set*.

## Examples

(defset Level :is (:the-ordered-set 'LOW 'MEDIUM 'HIGH))
(ask (successor Level 'LOW 'MEDIUM)) ==> T
(retrieve ?x (successor Level 'MEDIUM ?x)) ==> (HIGH)

## See Also

Last modified: Jun 1 1995