Partonomic Relationships and SEP Triples COMP60421 Sean Bechhofer - - PowerPoint PPT Presentation

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Partonomic Relationships and SEP Triples

COMP60421 Sean Bechhofer University of Manchester sean.bechhofer@manchester.ac.uk

• Material kindly provided by Patrice Seyed, University of Buffalo

Partonomy

• Representing and reasoning on relationships such subclass-of (for

generalization) and part-of (for aggregation) is crucial for medical information systems.

• Is part-of transitive?

– usage must be consistent

• Generally transitive for anatomy

– The femur is part of the leg, leg is part of the body therefore femur is part of the body

• Part-Whole specialization

– inheritance of roles along a part-whole taxonomies

• Fracture of the Femur is a fracture of the Leg
• Representation and Reasoning must handle cases where this sort of

inference does not hold – Transplantation of the Aorta is not a Transplantation of the Heart – Amputation of a Finger is not Amputation of the Hand. – Myocarditis is not an Inflammation of the entire Heart (Pancarditis).

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Part-Whole

• Mechanisms to support this include
• Right Identities

– e.g. GRAIL – hasLocus inherited across isPartOf

• Property chains

– (hasLocation o hasPart) subClassOf hasLocation

• Explicit use of Disjunction

– Heart Disease is a Disease located in Heart or some part of Heart

• Structure-Entire-Part Triples

– Separate classes for the the whole of the parts (S), the whole (E) or parts (P).

• Each approach places different requirements on the representation and

potentially introduce different cognitive complexities.

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Partonomic Relationships

• How can we capture this sort of reasoning while staying within a language

with restricted expressiveness? – ALC does not offer transitive relationships

• S-E-P Triples
• Part-Whole reasoning is implicitly done via subsumption reasoning (when

and where transitive roles/property chains deemed expensive)

• SEP triples implicitly express part-whole relationships between anatomical

entities

• An(other) example of an Ontology Design Pattern

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SEP Triples

• For each entity X, we introduce XS, XE and XP.
• ’S’ stands for a Structure Class

– Individuals that are a part of a “whole” entity – HeartS : a part of the heart or a whole heart

• Two subclasses: ‘E’ and ‘P’ Class for Entire and Part Class

– HeartE : an entire heart – HeartP : a part of a heart

• Use appropriate subclass for definitions

5 HeartS HeartE HeartP

SEP Triples

• SEP triples given for all anatomical entities
• Body

– (BodyS, BodyE, BodyP)

• Heart

– (HeartS, HeartE, HeartP)

• Myocardium

– (MyocardiumS, MyocardiumE, MyocardiumP )

• Connecting axioms

– HeartS SubClassOf: BodyP

• Appropriate class then used for a definition.

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HeartS HeartE HeartP MyocardiumS MyocardiumE MyocardiumP BodyS BodyE BodyP

Entailment

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Entailment based

• n Partonomic

Relationships

Class: Carditis EquivalentTo: Inflammation and (hasLocus some HeartS)

• Class: Myocarditis

EquivalentTo: Inflammation and (hasLocus some MyocardiumS)

HeartS HeartE HeartP MyocardiumS MyocardiumE MyocardiumP Carditis hasLocus Myocarditis hasLocus

Carditis is an inflammation of the Heart or one of its parts Myocarditis is an inflammation of the Myocardium or one of its parts

Non Entailment

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No Entailment!

Class: Pancarditis EquivalentTo: Inflammation and (hasLocus some HeartE)

• Class: Myocarditis

EquivalentTo: Inflammation and (hasLocus some MyocardiumS)

HeartS HeartE HeartP MyocardiumS MyocardiumE MyocardiumP Pancarditis hasLocus Myocarditis hasLocus

Pancarditis is an inflammation of the entire Heart

SEP Triples

• All very nice, but the SEP approach doesn’t actually model the relational

structure of parthood. – Rather partonomic “level” -- whether things are a whole or a part.

• Alternatives introduce explicit relationships, but require additional

expressivity in the representation. – Effect on computational resources needed. – Potential effect on the cognitive complexity

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Alternative 1

• Introduce explicit definitions for the “structure” and “part” entities, using a

new transitive, reflexive relationship partOf

• But, needs transitive properties and disjunction.
• Also, reflexive nature of partOf results in equivalences.

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Class XE Class XS EquivalentTo: XE or (partOf some XE) Class XP EquivalentTo: (partOf some XE)

Alternative 2

• Replace the use of XS with X or (partOf some X)
• Replace the use of XE with X
• Replace axioms of the form XS SubClassOf: YP with

X SubClassOf (partOf some Y)

• Removes the SEP triples altogether, but requires disjunction

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Alternative 3

• Introduce a property properPartof, subproperty of partOf.

– Encapsulates “proper” subparts (e.g. not the whole)

• Replace the use of XS with X or (partOf some X)
• Replace the use of XE with X
• Replace axioms of the form XS SubClassOf: YP with

X SubClassOf (properPartOf some Y)

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Querying Structure

• Finding things that are located in the entire, part or structure

13 Entire Part Structure O hasLocus some HeartE hasLocus some HeartP hasLocus some HeartS A1 hasLocus some HeartE hasLocus some HeartP hasLocus some HeartS A2 hasLocus some Heart hasLocus some (partOf some Heart) hasLocus some (Heart

• r (partOf some Heart))

A3 hasLocus some Heart hasLocus some (properPartOf Heart) hasLocus some (partOf some Heart)

Partonomic Relationships

• SEP triples capture some aspects of part-whole.
• Original SEP approach doesn’t actually model the relational structure of

parthood. – Rather partonomic “level”

• Alternatives do, but require additional expressivity in the representation.

– Effect on computational resources needed.

• Choice may not always be good!

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