=== Base Template !UnionOf2Classes ===

[[br]]!UnionOf2Classes is a template for expressing that a class is the union of two classes. 
[[br]]
[[br]]!UnionOf2Classes(a, b, c) means that a, b, and c are classes, and that c is the union of a 
and b. 
[[br]]
[[br]]Roles: 
[[br]]1 hasClass1 Class 
[[br]]2 hasClass2 Class 
[[br]]3 hasClassUnion Class 

Axiom: 
{{{
UnionOf2Classes(x1, x2, x3) <-> 
Class(x1) & 
Class(x2) & 
Class(x3) & 
exists y(EnumeratedSetOf2Classes(x1, x2, y) & 
UnionOfSetOfClassTemplate(y, x3)) . 
}}}

NOTE See 8.3 for further information on the representation used in this template.