R20 - modelint/shlaer-mellor-metamodel GitHub Wiki

R20 / 1:M

Attribute characterizes exactly one Class

Class is characterized by one or many Attribute

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An Attribute expresses a characteristic that describes all instances of a Class.

Since a Class must have at least one Identifier, and an Identifier consists of at least one Attribute, it follows that a Class requires at least one Attribute.

By definition, an Attribute is defined as a property of a single Class.

Formalization

Attribute.(Class, Domain) -> Class.(Name, Domain)