Search and Navigate Web Ontologies

hurriedtinkleΤεχνίτη Νοημοσύνη και Ρομποτική

15 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

78 εμφανίσεις

1

Search and Navigate

Web Ontologies

Li Ding

Tetherless World Constellation

Rensselaer Polytechnic Institute


Aug 22, 2008

2

Outline


Background


Enabling Search and Navigation Graph on
Swoogle


Enabling Collaborative Ontology
Repository on Semantic Wikis

3

Online Ontology: Past and Future


Pre
-
Web era (e.g. cyc, wordnet)


[semantics] define terms semantics, and interlink terms


[access] ontology available via local files, database, and KB


Now (e.g. foaf)


Increasing adoption of semantic web languages


[access] published and shared on the Web


Term identified by HTTP URI, support hyperlink


Web 3.0 era (e.g. tw.rpi.edu)


Native semantic web support


[semantics] preserve provenance information (history, author)


[access] collaboratively maintained on Semantic Wiki


Flexible ownership/edit granularity


Dynamic update and growth

In what follows, we focus on semantic web ontolgoies

4

SW Ontology: Conceptual Model

wordNet:Agent

rdf:type

rdfs:Class

rdfs:subClassOf

foaf:Person

http://xmlns.com/foaf/0.1/index.rdf

foaf:mbox

rdfs:domain

rdf:type

rdf:Property

ex:Li

foaf:mbox

rdf:type

dingl@cs.rpi.edu

foaf:Person

http://www.cs.rpi.edu/~dingl/foaf.rdf

class

property

SW Ontology

Instance Data

SW Document

Meta Term

t1

t2

t4

t3

foaf:mbox

t5

t6

SW Term Usage


Define class
(t2)


Define property
(t4)


Reference class
(t1)


Reference property
(t3)


Instantiate class
(t5)


Instantiate property
(t6)

Namespace

instance

http://xmlns.com/foaf/0.1/

5

Enabling Search and Navigation
Graph (SNG) on Swoogle


Online ontology is not merely a web page,
so users need effective means to access
ontology at different levels of granularity.

6

Namespace

SW Document

SW Ontology

1

2

6

3

hyperlink

hyperlink

imports

Term description

7

uses

Search and Navigation Graph:

Without Search Engine


Both term and ontology are navigation stops


Native semantic navigation (4,5,6,7), e.g. doc => term1


Native Web navigation (1,2,3), e.g. onto1.t1 => onto2.t2


Term lookup (match by name), e.g. fine concept person

Meta Term

5

defines

Term

lookup

string

instantiates

4

7

Example: Browsing Ontology and Terms
in Ontology Editor


8

What Else is Wanted?


Better search interface


How do I find terms related to “green tea”


How do I find documents related to “Li Ding”


More navigation paths


How to find instances of foaf:Person


How to find documents defining foaf:Person


Utilizing instance data


What class is frequently used as the domain
of dc:title ?

9

Example: Homepage of Term

navigation paths

Ranked description aggregation

Surf to another term

10

Namespace

SW Document

SW Ontology

1

2

6

3

5

defines

hyperlink

hyperlink

imports

Term description

7

uses

Search and Navigation Graph:

Adding Keyword Search

Semantically generate text metadata for term and ontology


Keyword search (8,9), e.g. keywords => term


Refined keyword search, e.g. prefix:keyword=> term

Meta Term

Term

Search



Document

Search

Keywords

8

9

lookup

instantiates

4

11

Example: Term Search


Ontology search: search for a collection of concepts


Term search: search for one concept


Term search can support auto
-
completion via : label:agent

More term search options:
http://swoogle.umbc.edu/index.php?option=com_swoogle_manual&manual=search_swt


label
:


the lexeme of Term's local
-
name. e.g.


'SeaFood' has two labels: 'sea' and 'food'

Keyword

search

Results

ranked by

popularity

12

Namespace

SW Document

SW Ontology

1

2

6

3

5

defines

hyperlink

hyperlink

imports

Term description, empirical relation

7

uses

Search and Navigation Graph:

Enriching Navigation Paths

Use search engine metadata to improve navigation paths


Inverse navigation path (4,5,7), e.g. namespace => term


Empirical relation (6), e.g. dc:title => foaf:Person

Meta Term

Term

Search



Document

Search

Keywords

8

9

lookup

4

instantiate

13

Example: Query based navigation


Navigate from class to documents containing instance data

Query Docs By

Term usage

Meta usage

14


foaf:name

rdfs:domain

Onto 1

owl:Class

rdf:type

foaf:Agent

rdfs:subClassOf

Onto 2



dc:title

rdf:type

Dr.

SWD3

foaf:Person

foaf:Person


foaf:name

rdfs:domain

foaf:Person

owl:Class

rdf:type

foaf:Agent

rdfs:subClassOf

foaf:Person

wob:hasInstanceDomain


dc:title

wob:hasInstanceDomain

Tim Finin

foaf:name

Empirical Relations


May not be defined in ontology, e.g. FOAF uses rdfs:seeAlso


May be Inductively learned from instance data

15

Example: Empirical Navigation


I
-
domain (p2c): the listed terms have been instantiated
(by
doc_freq

semantic web documents) as the domain of
the specified term
http://webns.net/mvcb/generatorAgent


16

Summary: Enabling Search and
Navigation Graph in Swoogle


Key technologies


Keyword search


natural language UI


Query based navigation


enrich navigation path


Ranking


promote reuse


Provenance


Each SNG node has an aggregated homepage,
enable global view


Version cache


ensure permanency


Implementation highlights


19 REST web services
, implemented as JAVA servlet, outputs
are in encoded in RDF (using WOB and SWOOGLE ontology)


Web interface (
http://swoogle.umbc.edu
), implemented using
PHP, provide HTML interface for access web services and
retrieve query results

17

Enabling Collaborative Ontology
Repository on Semantic Wikis

Interestingly enough, the search and
navigation graph (SNG) nicely fits
the structure of Semantic Wikis

18

Authoring Ontologies on

Semantic Wiki


Wiki natively supports


Collaborative edit: user login, online editing


Provenance tracking: revision history, authors


Navigation: wiki
-
link, external
-
link, “what links here”


Semantic Wiki supports


HTML and RDF homepage for each term (class,
property, instance) and ontology


RDFS inference, and potentially some OWL inference


Allow coexistence of ontology and instance


Conventional ontology editing UI via (i) template or (ii)
semantic form + auto
-
completion

19

Highlight 1: Wiki Homepage for Each
Term and Ontology (SNG node)


20

Highlight 2: Provenance Preserving
Concept Convergence


Concept Convergence


One latest revision


Multiple authors


Dynamic concept may
have many revisions


Stable concept may be
“Protected”


Provenance in history


Author


Change date


Changed content


Change notes

21

Highlight 3: Supporting Multiple
Ontologies


Concpets from different ontologies may
stay together and be connected

22

Summary: Enabling Collaborative
ontology repository on Semantic Wikis


Key technologies evaluation


Concept modeling


capable of RDFS, OWL, OBO storage


Keyword search
-

wiki native search is not enough


Navigation


absorb Swoogle technology


Ranking


absorb Swoogle technology


Provenance


add semantic history


Implementation highlights


http://tw.rpi.edu/

is an experimental work, which develops
ontology for annotating instances


Semantic Mediawiki (SMW) and a selection of SMW extensions
as the infrastructure


A set of wiki templates and semantic forms (in form of special
wiki pages) for improving user interface