Verifies that a given frame is the minimal common superclass of two other frames, or returns the minimal common superclass of two classes.


A class.
A class.
Either a frame to be tested or a variable to be bound.


  (:LEAST-COMMON-SUPERCLASS Canines Bacteria Animals)
  (:LEAST-COMMON-SUPERCLASS Alligators Dogs  ?what)

Success criteria

Each class argument must be a class. If the clause is ground, succeeds if the relationship is true. If the clause is not ground, succeeds if can retrieve a minimal common superclass.

Failure criteria

Fails if the class arguments are not classes or if the two frames have no minimal common superclass.


The minimal common superclass is a class that is a parent class of both class1 and class2, and that has subclass that is also a common superclass of class1 and class2.

A KBMS is encouraged to always return a value for this relation.

Related commands

Back to...

Algernon commands
Algernon Documentation Central
Algernon home page