Practical Temporal Ontology and Markup Language University of Rochester

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1 Practical Temporal Ontology and Markup Language University of Rochester George Ferguson November

2 Practical Temporal Ontology & ML Overall Program Summary Problem: Temporal information is ubiquitous in real-world environments. How should we represent it? How do we get it? How do we use it? Strategy: Develop appropriate temporal ontologies and markup languages Develop tools for using them and evaluate their use Approach: General ontology of Time Practical Temporal Ontology and markup language PTO Editor with integrated TimeLogic2 temporal reasoner 1

3 DAML-Time/OWL-Time: An Upper Ontology of Time Problems: No community consensus (Hobbs, Allen, SUMO, CYC,...) Difficult to avoid philosophical over-commitments Solution: Consensus achieved primarily thanks to Jerry Hobbs leadership Contributions: Emphasis on the topological (interval) relations and the relationship between time and events Specialization of DAML-Time to ITL Automated and semi-automated translation of DAML-Time to RDF/DRS DAML-Time/OWL-Time website 2

4 DAML-Time/OWL-Time: An Upper Ontology of Time 3 Dec 1, 2004

5 Practical Temporal Ontology and Markup Language 4 Problems: How to represent temporal information from real-world documents? How could anyone use such a complicated temporal ontology? Solution: Develop practical temporal ontology Motivated by our experience with: Natural language processing Automated and human-in-the-loop planning Specify corresponding markup language for documents

6 Practical Temporal Ontology and Markup Language Based on Interval Temporal Logic (Allen algebra) Relation Before(i, j) Meets(i, j) Overlaps(i, j) Starts(i, j) During(i, j) Finishes(i, j) i Inverse After(i, j) MetBy(i, j) OverlappedBy(i, j) StartedBy(i, j) Contains(i, j) FinishedBy(i, j) Relations grouped into three classes: No gaps: Equals, Meets, MetBy, Starts, StartedBy, Finished, FinishedBy One gap: Before, After Two gaps: During, Contains, Overlaps, OverlappedBy Common disjunctive relations: Disjoint, etc. Temporal durations for gaps j 5

7 Practical Temporal Ontology and Markup Language Practical Temporal Ontology: XML markup <?xml version="1.0" encoding="us-ascii"?> <!DOCTYPE document SYSTE M "pto-docu ment.dtd"> <document> The venue was set,the Rolling Stones and theirfriends w ere confirmed and the tickets were sold.however, after only <event id="e1" duration="2" units="months">two months of planning</event> <event id="e2">crowd controlexperts were stilpredicting thatthe concert to benefit SARS-struck Toronto was a blueprintfor disaster</event>. Organizers sold over 400,000 tickets to the <event id= e3 >show</event> that was held at an abandoned military base. Thatsame base hosted <event id="e4" duration= 1" units= day">the Pope's World Youth Day</event> <event id="e5" duration= 1" units= year">last year</event>. <relation id="r1" type="after" arg1="e2" arg2="e1"/> <relation id="r2" type= During" arg1="e4" arg2="e5"/> </document> 6

8 Practical Temporal Ontology and Markup Language Could people use it? How would they use it? Ontologies are complicated Temporal ontologies are complicated Markup is complicated Solution: Develop a tool to help them... 7

9 PTO Editor Graphical editor to support human markup of temporal information in natural language documents Interface specialized for Practical Temporal Ontology Events Relations Output in XML and OWL Original plan: Evaluate human performance and revise ontology as needed Final plan: Integrate temporal reasoner to show value of semantic markup 8

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20 PTO Editor <?xml version="1.0" encoding="us-ascii"?> <!DOCTYPE rdf:rdf [ <!ENTITY pto " ]> <rdf:rdf xmlns = " xmlns:pto = "&pto;" xmlns:rdf = " w.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs = " w w.w3.org/2000/01/rdf-sche m a#" xmlns:owl = " > <owl:ontology rdf:about=""> <owl:imports rdf:resource=" ml/owl/pto.owl"> </owl:ontology> <pto:eventrdf:id="e1"> <pto:duration> <pto:duration> <pto:dquantity> 2 </pto:dquantity> <pto:dunits rdf:resource="&pto;months"/> </pto:duration> </pto:duration> <pto:description> planning </pto:description> </pto:event>... <pto:after rdf:id="r1"> <pto:arg1 rdf:resource="#e2"/> <pto:arg2 rdf:resource="#e1"/> <pto:gap> <pto:durationalconstraint> <pto:quantity> 2 </pto:quantity> <pto:units rdf:resource="#months" /> </pto:durationalconstraint> </pto:gap> </pto:after> 19

21 TimeLogic2 Java reimplementation of temporal reasoner for Interval Temporal Logic (Allen algebra) Original in Lisp c New version fully-documented, carefully designed to support future development/pedagogy Includes optimized implementation using Java primitive types to represent relations Not all features of original TimeLogic implemented: Durations Reference intervals Part of SemWebCentral distribution 20

22 Practical Temporal Ontology & ML Milestones and Accomplishments OWL-Time ontology & website Practical Temporal Ontology PTO Editor TimeLogic

23 Practical Temporal Ontology & ML Transition/Handoff Developed and maintained the DAML-Time website: Prototype PTO editor on SemWebCentral: Includes TimeLogic2 22

24 Practical Temporal Ontology & ML Remaining Issues Representing and using temporal information is still a huge challenge (and opportunity) Production of ontology-aware temporal information from structured sources Automatic markup of natural sources via NLP Both of these would enable automated reasoning about the temporal information Human use of ontologies is still an art This is an issue for moving beyond knowledge engineers Although not nearly everyone who uses the web understands HTML, still you don't have to be a professional editor or typesetter to use it, especially for relatively simple tasks Need to evaluate whether proposed ontologies are more or less general rather than idiosyncratic Inter-annotator agreement (e.g., kappa) would be the right way to go Tools should complement and augment human abilities 23

25 Practical Temporal Ontology & ML Summary Temporal information is everywhere in real-world settings and vital for real-world reasoning How should we represent it? Develop appropriate temporal ontologies and markup languages OWL-Time, Practical Temporal Ontology How do we get it? Develop ontology-based tools and evaluate their use PTOEditor supports human markup of temporal information How do we use it? Ontology-based markup enables automated reasoning TimeLogic2 Interval Temporal Reasoner integrated with PTOEditor 24

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