SysML "shared" Property challenge as objects: two Triangles share one LineSegment edge.

There are Links from t1 to e1, e2, and the "shared" e3, each typed by the anonymous Association from Triangle to LineSegment. So the Slot in t1 corresponding to Property edge is populated with e1, e2, e3.

Similarly, there are Links from t2 to the "shared" e3, e4, e5, each typed by the anonymous Association from Triangle to LineSegment. So the Slot in t2 corresponding to Property edge is populated with e3, e4, e5.

You would definitely not want to use AggregationKind::composite, because you don't want to destroy every edge when you destroy one triangle; but AggregationKind::none "feels" too weak. There is some sense in which each triangle aggregates its edges, so AggregationKind::shared lends itself well.

Nice! You can now win beers when you go drinking with your SysML colleagues and someone challenges you to use 'shared' aggregation meaningfully. Well maybe meaningfully enough for you; can't actually guarantee you'll win that beer.

Visit also: SysMLv1: TIP: You can strengthen the ill-defined semantics of Property 'aggregation' (an AggregationKind) by applying custom Stereotypes to a Property, documented with its intended use. Not perfect, but better than not. EXAMPLE: «assembled»

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More block Generalization examples: Home entertainment system

Notes

[NAMING, POLICY]{STRICT} Use singular Property names, let the multiplicity indicate plurality.

Snippets (quotes/extracts)

[SysML-1.7] A property typed by a Block that does not have composite aggregation is classified as a reference property.

[SysML-1.6] SysML also supports properties with shared aggregation, as shown by a white diamond symbol on an association.

[SysML-1.6] Like UML, SysML defines no specific semantics or constraints for properties with shared aggregation, but particular models or tools may interpret them in specific ways.

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Visit also (backlinks)

SysMLv1: TIP: You can strengthen the ill-defined semantics of Property 'aggregation' (an AggregationKind) by applying custom Stereotypes to a Property, documented with its intended use. Not perfect, but better than not. EXAMPLE: «assembled»