On t Ologies and Tools

7/29/2019 On t Ologies and Tools

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Ontologies and tools

Natalya Fridman Noy

Stanford Medical InformaticsStanford University


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Ontologies and tools?

Managing multiple ontologies

using several ontologies simulteneously

creating mapping between ontologies

ontology merging and alignment

Managing large ontologies

scaling up

presentation

Connecting to otherrepresentation

formalisms


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Outline

HPKB: ontology-development

experience

Today: Tools we have now

as part of standard Protg

as plug-ins

Tomorrow: Tools we toolsneed

functionality


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HPKB: High-Performance

Knowledge Bases

Mission statement

enable system developers to rapidly

construct large knowledge bases

(100K-1M axiom/rule/frame in several months)

Building

FoundationKnowledge

Acquiring

DomainKnowledge

Performing

Efficient

Problem

Solving

Domain experts

play

important role


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COA Architecture


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Development and Evaluation

Cyc upper level

Knowledge

Acquisition

tools

Problem-

solving

methods

Domain

ontologies

Critiquers

Critiquers

Critiquers

Knowledge

Acquisition

tools

Knowledge

Acquisition

tools

Problem-

solving

methods

Problem-

solving

methods

Evaluation

Evaluation


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SMI in HPKB

Protg was used as KA tool

What we gained:

new Protg widgets

instance table

contains widget

HPKB tab - summary of large collection ofinstances

opportunity to test usability of Protg

(August 24-30)


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HPKB Tab


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SMI in HPKB

Ontology alignment

Loom to Protg

Manual alignment and merging in Protg

Protg to Cyc


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Outline

HPKB: ontology development

experience

What we have now


as plug-ins

What is needed

functionality

tools


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Ontology-management tools

in Protege

Ontology-inclusion mechanism

include other Protg ontologies

somewhat transparent

Metrics

collect information on the current ontology


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Included ontologies - features

Include multiple ontologies

Included ontologies identified by color

Included ontologies cannot be edited

Current ontology can use all the

concepts from the included ontology

The Protg knowledge model ontology

is included in this way


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Included ontologies

need to know

Included projects should be in the same

directory

Name space conflicts are not resolved

Project name is part of instance name

Users need to fix class-name and slot-

name conflicts


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Metrics


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Outline


experience

What we have now


as plug-ins

What is needed

functionality

tools


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Ontology-management

plug-ins

Protg-to-Cyc tab

SMART: ontology merging and

alignment

???


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Bridging the Semantic Gap

Cyc and Protg adopt different

knowledge models

Protg uses OKBC with some extensions

(essentially frame-based)

Cyc uses CycL (essentially rule-based)

Our solution has been to define anOKBC Microtheory within Cyc


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1. Define a Microtheory (MT)

of OKBC predicatesOKB

C Default Mt : OKBCMt .

constant: OKBCDomain.

isa : BinaryPredicate.

arg1Isa : BinaryPredicate .arg2Isa : Collection .

comment : "(OKBCDomain PRED COL) means that COL is one of the possible

domains for PRED. A predicate can have several domains. The first

argument to a predicate has to be an instance of one such domain. Note

that this is different from arg1Isa: If there are several assertions

(arg1Isa PRED COL1) ... (arg1Isa PRED COLN), then the first argument to

PRED has to be an instance of all of them: COL1, ... COLN".

F:

(implies (?PRED ?INS1 ?INS2)

(thereExists ?COL

(and (OKBCDomain ?PRED ?COL)

(isa ?INS1 ?COL)))).


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2. Create a Domain-Specific MT

as an Extension to the OKBC MT

COA

genlsMT

(fi-assert '(#$isa #$artillery-type #$BinaryPredicate) #$ConstraintsMt)

(fi-assert '(#$isa #$frontage-size-lower #$BinaryPredicate) #$ConstraintsMt)

(fi-assert '(#$isa #$readiness #$BinaryPredicate) #$ConstraintsMt)

(fi-assert '(#$isa #$formation-flexibility #$BinaryPredicate) #$ConstraintsMt)

(fi-assert '(#$isa #$task #$BinaryPredicate) #$ConstraintsMt)

(fi-assert '(#$isa #$description #$BinaryPredicate) #$ConstraintsMt)

(fi-assert '(#$isa #$checked-resource #$BinaryPredicate) #$ConstraintsMt)

(fi-assert '(#$OKBCDomain #$day-or-night #$Unit-Rate-Of-Movement-Check)

#$ConstraintsMt)

(fi-assert '(#$OKBCRange #$day-or-night #$Thing) #$ConstraintsMt)

(fi-assert '(#$arg2Format #$day-or-night #$SetTheFormat) #$ConstraintsMt)(fi-assert '(#$OKBCDomain #$desired-position

#$Artillery-Unit-Firing-Position-Check) #$ConstraintsMt)

(fi-assert '(#$OKBCRange #$desired-position #$Thing) #$ConstraintsMt)

(fi-assert '(#$arg2Format #$desired-position #$SetTheFormat) #$ConstraintsMt)

(fi-assert '(#$OKBCDomain #$echelon #$Deployment) #$ConstraintsMt)

(fi-assert '(#$OKBCRange #$echelon #$Thing) #$ConstraintsMt)

.

OKB

C


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3. Cycs Theorem Prover Draws

Appropriate Inferences

Results

(#$implies (#$and (isa ?CONSTR

Unit-Combat-Power-Check)(unit-specialty-type ?CONSTR ?COL)

(isa ?UNIT ?COL)

(echelon-type ?CONSTR ?ECH)

(echelonOfUnit ?UNIT ?ECH)

(combat-power ?CONSTR ?N))(combatPowerOfUnit ?UNIT ?N))

COA

genls

MT

OKB

C

genlsMT


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SMART: Ontology Merging

and Aligment

What is needed

Help and guidance in the process

Specialized tools for ontology merging

and alignment

What is not needed (not yet feasible)

Fully automatic merging and alignment

tool


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Mapping, Merging, Alignment

car

vehicle

car

vehicle

vehiclecar


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Approaches to Ontology

Merging and Alignment

Conflict resolution after merging

+ direct results

can be overwhelming hard to repeat

Morphing before merging

+ process can be repeated

no direct results

Direct manipulation tools

+ can manipulate the result directly

harder to repeat, but still possible


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SMART Approach to Merging

and Alignment

Define a set of ontology merging and

alignment operations

Develop an algorithm for ontology

merging and alignment Perform some operations automatically

Guide the user to other operations

Design and implement specialized tool

for ontology merging and alignment


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Setup:load files, set preferences, ...

Execute operation:perform automatic updates,detect conflicts,

create suggestions

Select operation:choose from suggestion list,

create a new operation, .

Initial suggestions:identical names, synonyms,superclasses for top-level classes in alignment

SMART Algorithm


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Example: merge classes

Automatic updates: Creating the new frame

Updating of references

Merging of attached slots

with identical names

Conflicts: Duplicate frame names

Merging of attached slots

with identical names but

different facets

Class Cityname:String

population:Integer

area:Float

Class Townname:String

populace:Integer

area:Area

Class Location Class Geographic-Location


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Example: merge classes (contd)

Suggestions:

Increase priority for current

suggestions with referenced

frames

Suggestions:

Increase priority for merging

operations that involve

frames in the same role,

such as superclasses,

subclasses, facet values

Class Cityname:String

population:Integer

area:Float

Class Townname:String

populace:Integer

area:Area

Class Location Class Geographic-Location


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Suggestions (contd)

Suggestions based on structural indications:

remove superclasses

remove subclasses

Class Customer

Class Travel agent

Class Individual

Class Driver

Class Driver


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Source ontology: car rental


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Source ontology:

airline reservations


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Explanations

Suggestions

Current

conflicts

Possible

solution


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Features of SMART

Feedback to the user

explanations

solutions for conflicts

Maintaining focus

re-ordering of suggestions

creating temporary frames to defer conflict

resolution Tracking relations

preserving reference relations

preserving mapping information


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Future directions

Extensions to the model

More extensive treatment offacets

Extensions to non-OKBC frameworks

Incorporation ofaxioms

Formal evaluation


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Outline


experience

What we have now


as plug-ins

What is needed

functionality

tools


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Wish-list: multiple ontologies

Managing multiple ontologies

opening multiple ontologies in one window

with equal status (unlike inclusion)

copying and moving frames between

ontologies

what should be copied? what to do with name conflicts?

Should we even bother?

information overload


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Wish-list: import and export

Import from and export to other

knowledge representation systems

general OKBC back end

Cyc to Protege

PowerLoom and back

Other KR formalisms

Wi h li t


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Wish-list:

creating ontology mapping

Mapping and alignment is not

always possible, because:

Cannot change sources

Want to keep sources separate

Cannot agree on a single

terminology

Similar problem: multiple views

vehiclecar

Wi h li t


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Wish-list:

large-scale ontologies

Managing large ontologies

scaling up to huge knowledge sources

different user interface

summary

overview

Date post:	03-Apr-2018
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