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Representing the UMLS Semantic Network using OWL Vipul Kashyap 1 and Alex Borgida 2 1 LHCNBC, National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894 2 Department of Computer Science, Rutgers University, New Brunswick, NJ 08903.
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Representingthe UMLS Semantic Networkusing OWL Vipul Kashyap1 and Alex Borgida2 1 LHCNBC, National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894 2 Department of Computer Science, Rutgers University, New Brunswick, NJ 08903 Seminar Prinzipien des Ontological Engineering Leipzig, 15.01.2004 Kristin Lippoldt Email: kristin.lippoldt@imise.uni-leipzig.de
Outline • The UMLS Semantic Network (SN) • Representation of SN using OWL • Multiple interpretations of „link“ • Evaluation of the interpretation variants • Methodology for choosing the „right“ representation variant (first steps)
The UMLS Semantic Network • nodes = semantic types • links = semantic relationships • two high level is-a hierarchiesEntity, Event • is-a hierarchie of relationshipsphysically_related_to, spatially_related_to, temporally_related_to, functionally_related_to, conceptually_related_to functionally_related_to affects is-a manages is-a
OWL • Web Ontology Language • Based on DAML+OIL • Description of classes, properties (e.g. relations between classes (e.g. disjointness), cardinality (e.g. "exactly one")) • Sublanguages: • OWL Lite (lower formal complexity than OWL DL, only cardinality values of 0 or 1) • OWL DL (maximum expressiveness, computational completeness ) • OWL Full (maximum expressiveness, syntactic freedom of RDF with no computational guarantees)
Description Logic - OWL Bacterium ODER Virus <owl:Class> <owl:unionOf rdf:parseType=“Collection”> <owl:Class rdf:about=“#Bacterium”/> <owl:Class rdf:about=“#Virus”/> </owl:unionOf> </owl:Class>
Representation of SN using OWL • Semantic Types OWL classes • Fungus Organism • Virus Organism • Semantic Relationships OWL properties • part_of physically_related_to • affects functionally_related_to • Properties of Semantic Network Relationships • Asymmetric relationships • has_part ≡ part_of • Symmetric relationships • adjacent_to ≡ adjacent_to
Semantics of a „link“ in the UMLS SN Bacteria Infection causes Two operators and : • (causes) = { x Bacteria (y)(y Infection causes(x,y)) }DL notation: (causes) ≡ causes.T • (causes) = { y Infection (x)(x Bacteria causes(x,y)) }DL notation: (causes) ≡ causes.T
Interpretation 1: / equals • axioms: causes.T ≡ Bacteria, causes.T≡ Infection • All Bacteria have to “cause” and all Infections have to“be-caused” (no others can participate in “causes”) b1 i1 b2 i2 b3 i3 b4
Interpretation 2: / subsumed • axioms: causes.T Bacteria, causes.T Infection • Not all bacteria need to “cause” not all infections have to “be-caused” (However no others can participate) i1 b2 i2 b3 i3 b4
Interpretation 3: / subsumes • axioms: Bacteria causes.T, Infection causes.T • All bacterias have to “cause” and all infections have to “be-caused”, but • A bacteria can cause a “non-infection” as well! • A “non-bacteria” can cause an infection as well! y1 i1 b2 i2 b3 i3 b4 x1
Interpretation 4: All/Some • axiom: Bacteria causes.Infection • All bacteria must “cause” some infection, but • A bacteria can cause a “non-infection” as well! • A “non-bacteria” can cause an infection as well! y1 i1 b2 i2 b3 i3 b4 x1
Interpretation 5: All/Only • axiom: Bacteria causes.Infection • All bacteria, if they “cause”, can cause only infections, but • Not all bacteria have to participate in the “causes” relationship • A non-bacteria can still cause an infection! y1 i1 b2 i2 b3 i3 b4
Interpretation 6: All/Each • axiom: Bacteria causes.Infection • Similar to a cross product, but • A bacteria can still cause a non-infection! i1 b2 i2 b3 i3 b4 x1
Interpretation 7: Some/Some • axiom: 1 (Bacteria causes.Infection) • There is at least one bacteria that “causes” at least one infection, but • A bacteria can still cause a non-infection! • A non-bacteria can still cause an infection! y1 i1 b2 i2 b3 i3 b4 x1
Interpretation 8: Some/Each • axiom: 1 (Bacteria causes.Infection) • There is at least one bacteria that “causes” all infections, but • A bacteria can still cause a non-infection! • A non-bacteria can still cause an infection! y1 i1 b2 i2 b3 i3 b4 x1
Summary of Interpretations • equals: causes.T ≡ Bacteria, causes.T≡ Infection • subsumed: causes.T Bacteria, causes.T Infection • subsumes: Bacteria causes.T, Infection causes.T • all/some: Bacteria causes.Infection • all/only: Bacteria causes.Infection • all/each: Bacteria causes.Infection • some/some: 1 (Bacteria causes.Infection) • some/all: 1 (Bacteria causes.Infection)
and Inheritance inheritance P(A,B) C A P(C,B) inheritance P(A,B) D B P(A,D) Example: process_of(BiologicFunction,Organism) C = PhysiologicFunction D = Animal • equals: no support of inheritance , A ≡ C • subsumed: no support of inheritance A C process_of.T
and Inheritance process_of.T process_of-.T • subsumes: supports both • all/some: supports inheritance,but not inheritance • all/only: supports inheritance,but not inheritance A B C D process_of.B process_of-.D A B C D process_of.B A C
and Inheritance process_of. D • all/each: supports both • some/some: no support of inheritance • some/all: doesn’t supports inheritance, but inheritance process_of. B A C
Blocking of Inheritance Example: Process_of(BiologicFunction,Organism) Process_of(MentalProcess,Plant) Modifying axioms: subsumes: P(A,B) C1 A and D1 B A C1 (P) and B D1 (P)
Methodologie für die Kodierung von Wissen im Semantic Web • Wahl der Kodierung • Unterstützung von Inferenz • Unterstützung der intendierten Anwendung • Nachvollziehbares Domänenmodell • Repräsentation in der Ontologiesprache
Unterstützung von Inferenzen • Welche Kodierung unterstützt Inferenz? • All/each und subsumes • Unterstützt die Kodierung nicht-intendierte Inferenzen? • Some/some unterstützt Aufwärts-Vererbung von Links • Kann etwas aus der Abwesenheit eines Links geschlussfolgert werden? • A P. B verbietet nicht, dass A in Relation zu B steht
Unterstützung der intendierten Anwendung • Ist es wichtig Inkonsistenzen zu erkennen? • Was sind Inkonsistenzen? • Wird die Kodierung diese Inkonsistenzen erkennen?
Nachvollziehbarkeit des Domänenmodells • Konzepte sind Kollektionen von Instanzen • Causes(Bacteria,Infection) • Was ist die intuitive Kodierung? • All/some and all/only wird von medizinischen Ontologien genutzt • All/each und some/some wurden abgelehnt • Gibt es alternative Interpretationen? • Aber: all/each erfüllt alle UMLS SN Anforderungen
Repräsentation in der Ontologiesprache • Grenzen von OWL • Negation und Disjunktion von Rollen • Kardinalität von Konzepten • Kann man weniger „teure“ Konstrukte verwenden? • Ressourcen fließen in die Komplexität der DL Operatoren
Conclusions and Future Work • Experiences in representing a real world “ontology”, the UMLS Semantic Network • Has been used very successfully • Requirements: / inheritance, inheritance blocking, polymorphic relationships • Presented multiple interpretations and encodings and evaluated their support for the UMLS Semantic Network requirements • Ontology developers and encoders on the Semantic Web might encounter similar requirements and possible encodings • Identified criteria for choosing between the various encodings • First steps towards a methodology which might be useful to ontology developers • Ongoing and Future Work • Semantic Vocabulary Interoperation Project • http://cgsb2.nlm.nih.gov/~kashyap/projects/SVIP • Use of OWL, RDF for improvement in Medical Information Retrieval