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Tools For Resolving Heterogeneity in Ontologies SKC Project Computer Science Department

. Tools For Resolving Heterogeneity in Ontologies SKC Project Computer Science Department Stanford University Gio Wiederhold, PI. Problem Addressed by SKC. Ontologies come from many autonomous sources Differing viewpoints (by source)

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Tools For Resolving Heterogeneity in Ontologies SKC Project Computer Science Department

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  1. . Tools For Resolving Heterogeneity in Ontologies SKC Project Computer Science Department Stanford University Gio Wiederhold, PI Gio Wiederhold SKC RKF 1

  2. Problem Addressed by SKC Ontologies come from many autonomous sources • Differing viewpoints (by source) • differing coverage vehicles (DMV, AIA) • differing granularity trucks (shipper, manuf.) • differing terms for similar items { lorry, truck } • same terms for dissimilar items trunk(luggage, car) • Created by focused groups • high quality used in commerce • ongoing maintenance annual models • Poor precision when merged ok for web browsing , poor for business Gio Wiederhold SKC RKF 2

  3. No committee is needed to forge compromises * within a domain Domains and Consistency . • a domain will contain many objects • the object configuration is consistent • within a domain all terms are consistent & • relationships among objects are consistent • context is implicit Domain Ontology • Compromises hide valuable details Gio Wiederhold SKC RKF 3

  4. Heterogeneity among Domains If interoperation involves distinct domains mismatch ensues • Autonomy conflicts with consistency, • Local Needs have Priority, • Outside uses are a Byproduct Heterogeneity must be addressed • Platform and Operating Systems 4 4 • Representation and Access Conventions 4 • Naming and Ontology : Gio Wiederhold SKC RKF 4

  5. SKC SKC Objective Provide for Maintainable Ontologies • devolve maintenance onto many domain-specific experts / authorities • provide an algebra to compute composed ontologies that are limited to their articulation terms • enable interpretation within the source contexts Gio Wiederhold SKC RKF 5

  6. Intersection create a subset ontology • keep sharable entries • Union create a joint ontology • merge entries • Difference create a distinct ontology • remove shared entries An Ontology Algebra A knowledge-based algebra for ontologies The Articulation Ontology (AO) consists of matching rules that link domain ontologies Gio Wiederhold SKC RKF 6

  7. Sample Operation: INTERSECTION Result contains shared terms, useful for purchasing Articulation Source Domain 1: Owned and maintained by Store Source Domain 2: Owned and maintained by Factory Gio Wiederhold SKC RKF 7

  8. Tools to create articulations Graph matcher for Articulation- creating Expert Transport ontology Vehicle ontology Suggestions for articulations Gio Wiederhold SKC RKF 8

  9. continue from initial point • Also suggest similar terms • for further articulation: • by spelling similarity, • by graph position • by term match repository • Expert response: • 1. Okay • 2. False • 3. Irrelevant • to this articulation • All results are recorded • Okay’s are converted into articulation rules Gio Wiederhold SKC RKF 9

  10. Based on processing headwords ý definitions using algebra primitives Candidate Match Repository Term linkages automatically extracted from 1912 Webster’s dictionary * * free, other sources . being processed. Notice presence of 2 domains: chemistry, transport Gio Wiederhold SKC RKF 10

  11. Using the Match Repository Gio Wiederhold SKC RKF 11

  12. Using the Match Repository Gio Wiederhold SKC RKF 12

  13. if [base_station.receiving] = true then satellite_data = [base_station] satellite_data.timestamp = now if [satellite_data.age] < 24 hours or [radio_jamming.level] > 30% then recon_data = [satellite_data] except when [flight_data.age] < 1 hour or [rain_sensor.daytotal] > 1 inch then recon_data = [flight_data] assert [recon_data] Rules for Real-Time Data Gio Wiederhold SKC RKF 13

  14. INTERSECTION support Articulation ontology Matching rules that use terms from the 2 source domains Terms useful for purchasing Store Ontology Factory Ontology Gio Wiederhold SKC RKF 14

  15. Arti- culation ontology Other Basic Operations DIFFERENCE: material fully under local control UNION: merging entire ontologies typically prior intersections Gio Wiederhold SKC RKF 15

  16. Features of an algebra Operations can be composed Operations can be rearranged Alternate arrangements can be evaluated Optimization is enabled The record of past operations can be kept and reused when sources change Gio Wiederhold SKC RKF 16

  17. Articulation knowledge for U (A B) U U U (B C) Legend: U (C E) U : union U (C E) U : intersection B) (A U U (B C) (C D) Knowledge Composition Composed knowledge for applications using A,B,C,E Articulation knowledge Knowledge resource E Articulation knowledge for Knowledge resource C U Knowledge resource A Knowledge resource B Knowledge resource D Gio Wiederhold SKC RKF 17

  18. Unary Summarize -- abstract Glossarize - list terms Filter - reduce instances Extract - move into context Binary Match - data corrobaration Difference - distance measure Intersect - use of articulation Union - search broadening Constructors create object create set Connectors match object match set Editors insert value edit value move value delete value Converters object - value object indirection reference indirection Primitive Operations Model and Instance Gio Wiederhold SKC RKF 18

  19. Exploiting the result . Avoid n2 problem of interpreter mapping [Swartout HPKB year 1] Result has links to source Processing & query evaluation is best performed within Source Domains & by their engines Gio Wiederhold SKC RKF 19

  20. What is the most recent year an OPEC member nation was on the UN security council? Related to DARPA HPKB Challenge Problem SKC resolves 3 Sources CIA Factbook ‘96 (nation) OPEC (members, dates) UN (SC members, years) SKC obtains the Correct Answer 1996 (Indonesia) Problems resolved by SKC Factbook has out of date OPEC & UN SC lists Indonesia not listed Gabon (left OPEC 1994) different country names Gambia => The Gambia historical country names Yugoslavia UN lists future security council members Gabon 1999 intent of original question Temporal variants Sample Processing in HPKB Gio Wiederhold SKC RKF 20

  21. Empowerment Domain Specialization . • Knowledge Acquisition (20% effort) & • Knowledge Maintenance (80% effort *) to be performed • Domain specialists • Professional organizations • Field teams of modest size automously maintainable * based on experience with software Gio Wiederhold SKC RKF 21

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