Part-Whole

UML distinguishes between aggregation and composition only. OntoUML distinguishes among

• sharing

  • shared part (white ◊)

  • exclusive part (black ♦)

• multiplicity of relationship

  • mandatory part with respect to the whole

  • mandatory whole w.r.t. the part

  • mandatory non-rigid type (e.g. role, phase, mixin)

OntoUML also distinguishes among various types of wholes and their parts

• functional whole (and ComponentOf relation)

• Collective (and SubCollectionOf and MemberOf relations)

• Quantity (and Containment and SubQuantityOf relations)

Examples

EX1:

EX2:

Notice that maximum multiplicity of the whole is > 1.

EX3:

Notice that maximum multiplicity of the whole is = 1.

EX4:

Optional part w.r.t. the rigid whole. The whole doesn´t necessarily need any part.

EX5:

Mandatory part w.r.t. the rigid whole. The whole does need a part, instances of the part may mute.

EX6:

Essential part w.r.t. the rigid whole. The whole does need a part, instances mustn´t mute.

EX7:

Optional rigid whole w.r.t. the part. The part may exist alone, even without the whole.

EX8:

Mandatory rigid whole w.r.t. the part. The part must belong to some whole, instances of the whole may mute.

EX9:

Inseparable part of the rigid whole. The part must belong to the same whole, instances of the whole mustn´t mute.

EX10:

Immutable part of the antirigid whole. Whenever the whole exists in the particular role or phase, its parts must be still the same instances – they cannot not mute. Compare to {essential}.

EX11:

Immutable whole w.r.t. the antirigid part. Whenever the part exists in the particular role or phase, its wholes must be still the same instances – they cannot not mute. Instances of the whole may mute only as the part changes it´s role or phase.

References:

GUIZZARDI, Giancarlo. Ontological Foundations for Structural Conceptual Models. Enschede: CTIT, Telematica Instituut, 2005. GUIZZARDI, Giancarlo. Introduction to Ontological Engineering. [presentation] Prague: Prague University of Economics, 2011.