Symmetric Perspective - modelint/shlaer-mellor-metamodel GitHub Wiki

A Unary Association has only one Perspective.

Given two instances (or the same instance related to itself) on a Unary Association, the role played by either side of the Association is identical.

There is, consequently, just one Symmetric Perspective.

For example, Territory borders Territory means the same thing for Territories A and B regardless of direction A->B or B->A. So A borders B means exactly the same as B borders A.

images/relationship-subsystem/symmetric-perspective-10.png

Therefore, only one phrase name, one multiplicity and one conditionality need be specified for a Unary Association.

Identifiers

1. Rnum + Domain

Attributes

No non-referential attributes