Tools For Resolving Heterogeneity Computer Science Department . Tools For Resolving Heterogeneity in Ontologies SKC Project Computer Science Department Stanford University Gio Wiederhold, PI 10/13/2018 Gio Wiederhold SKC RKF 1

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 10/13/2018 Gio Wiederhold SKC RKF 2

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 No committee is needed to forge compromises * within a domain Domain Ontology Compromises hide valuable details 10/13/2018 Gio Wiederhold SKC RKF 3

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 : 10/13/2018 Gio Wiederhold SKC RKF 4

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 SKC 10/13/2018 Gio Wiederhold SKC RKF 5

An Ontology Algebra A knowledge-based algebra for ontologies The Articulation Ontology (AO) consists of matching rules that link domain ontologies Intersection create a subset ontology keep sharable entries Union create a joint ontology merge entries Difference create a distinct ontology remove shared entries 10/13/2018 Gio Wiederhold SKC RKF 6

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 10/13/2018 Gio Wiederhold SKC RKF 7

Tools to create articulations Graph matcher for Articulation- creating Expert Vehicle ontology Transport ontology Suggestions for articulations 10/13/2018 Gio Wiederhold SKC RKF 8

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 10/13/2018 Gio Wiederhold SKC RKF 9

Candidate Match Repository Term linkages automatically extracted from 1912 Webster’s dictionary * * free, other sources . being processed. Based on processing headwords ý definitions using algebra primitives Notice presence of 2 domains: chemistry, transport 10/13/2018 Gio Wiederhold SKC RKF 10

Using the Match Repository 10/13/2018 Gio Wiederhold SKC RKF 11

Using the Match Repository 10/13/2018 Gio Wiederhold SKC RKF 12

Rules for Real-Time Data 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] 10/13/2018 Gio Wiederhold SKC RKF 13

INTERSECTION support Articulation ontology Matching rules that use terms from the 2 source domains Terms useful for purchasing Store Ontology Factory Ontology 10/13/2018 Gio Wiederhold SKC RKF 14

Other Basic Operations UNION: merging entire ontologies DIFFERENCE: material fully under local control Arti- culation ontology typically prior intersections 10/13/2018 Gio Wiederhold SKC RKF 15

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 10/13/2018 Gio Wiederhold SKC RKF 16

Knowledge Composition Composed knowledge for applications using A,B,C,E Articulation knowledge for U (A B) (B C) (C E) Articulation knowledge Legend: U : union U : intersection U (C E) Articulation knowledge for Knowledge resource E Knowledge resource C (A B) U U (B C) U (C D) Knowledge resource A Knowledge resource B Knowledge resource D 10/13/2018 Gio Wiederhold SKC RKF 17

Primitive Operations Model and Instance 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 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 10/13/2018 Gio Wiederhold SKC RKF 18

Exploiting the result . Processing & query evaluation is best 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 10/13/2018 Gio Wiederhold SKC RKF 19

Sample Processing in HPKB 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 10/13/2018 Gio Wiederhold SKC RKF 20

Domain Specialization . Knowledge Acquisition (20% effort) & Knowledge Maintenance (80% effort *) to be performed Domain specialists Professional organizations Field teams of modest size Empowerment automously maintainable * based on experience with software 10/13/2018 Gio Wiederhold SKC RKF 21