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

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 1

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). 2

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. 3

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 4

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 HeartS HeartE HeartP 5

SEP Triples • SEP triples given for all anatomical entities • Body BodyS – (BodyS, BodyE, BodyP) • Heart BodyE BodyP – (HeartS, HeartE, HeartP) • Myocardium – (MyocardiumS, MyocardiumE, MyocardiumP ) HeartS • Connecting axioms – HeartS SubClassOf: BodyP HeartE HeartP � • Appropriate class then used for a definition. MyocardiumS MyocardiumE MyocardiumP 6

Entailment Carditis is an inflammation of the Heart or one of its parts Carditis hasLocus HeartS HeartE HeartP Entailment based Myocarditis hasLocus MyocardiumS on Partonomic Relationships Myocarditis is an MyocardiumE MyocardiumP inflammation of the Myocardium or one of its parts Class: Carditis EquivalentTo: Inflammation and (hasLocus some HeartS) � Class: Myocarditis EquivalentTo: Inflammation and (hasLocus some MyocardiumS) 7

Non Entailment Pancarditis is an inflammation of the HeartS entire Heart Pancarditis hasLocus HeartE HeartP Myocarditis hasLocus MyocardiumS No Entailment! MyocardiumE MyocardiumP Class: Pancarditis EquivalentTo: Inflammation and (hasLocus some HeartE) � Class: Myocarditis EquivalentTo: Inflammation and (hasLocus some MyocardiumS) 8

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 9

Alternative 1 • Introduce explicit definitions for the “structure” and “part” entities, using a new transitive, reflexive relationship partOf � � Class XE � Class XS � EquivalentTo: XE or (partOf some XE) � Class XP � EquivalentTo: (partOf some XE) � � • But , needs transitive properties and disjunction. • Also, reflexive nature of partOf results in equivalences. 10

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 11

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) 12

Querying Structure • Finding things that are located in the entire, part or structure 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 hasLocus some (Heart some Heart) or (partOf some Heart)) A3 hasLocus some Heart hasLocus some hasLocus some (partOf (properPartOf Heart) some Heart) 13

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! 14