Isa and instance relationships

Two attributes isa and instance play an important role in many aspects of knowledge representation.

The reason for this is that they support property inheritance.

isa

- used to show class inclusion, e.g.

isa(mega_star,rich).

instance

- used to show class membership, e.g.

instance(prince,mega_star).

From the above it should be simple to see how to represent these in predicate logic.