Structural Web Search Using a GraphBased Discovery System

1
Structural Web Search Using a Graph-Based
Discovery System

• Nitish Manocha, Diane J. Cook, and Lawrence B.
  Holder
• University of Texas at Arlington
• cook_at_cse.uta.edu
• http//www-cse.uta.edu/cook

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Structured Web Search

• Existing search engines use linear feature match
• Web contains structural information as well
• Hyperlink information
• Web viewed as a graph Kleinberg
• Subdue searches based on structure
• Use as foundation of a structural search engine
• Incorporation of WordNet allows for synonym match

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SUBDUE

• Discovers structural patterns in input graphs
• A substructure is connected subgraph
• An instance of a substructure is a subgraph that
  is isomorphic to substructure definition
• Pattern discovery, classification, clustering

Input Database
Substructure S1 (graph form)
Compressed Database
triangle
shape
C1
S1
object
R1
R1
on
square
S1
S1
S1
shape
object
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Subdue Algorithm

• Start with individual vertices
• Keep only best substructures on queue
• Expand substructure by adding edge/vertex
• Compress graph and repeat to generate
  hierarchical description
• Optional use of background knowledge

5
Inexact Graph Match

• Some variations may occur between instances
• Want to abstract over minor differences
• Difference cost of transforming one graph to
  make it isomorphic to another
• Match if cost/size lt threshold

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Application Domains

• Protein data
• Human Genome DNA data
• Spatial-temporal domains
• Earthquake data
• Aircraft Safety and Reporting System
• Telecommunications data
• Program source code
• Web data

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Represent Web as Graph

• Breadth-first search of domain to generate graph
• Nodes represent pages / documents
• Edges represent hyperlinks
• Additional nodes represent document keywords

subdue
texas
projects
word
word
university
work
hyperlink
page
parallel
group
learning
robotics
planning
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WebSubdues Structural Search

• Formulate query as graph
• Use Subdues predefined substructure option to
  search for instances of query

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Query Find all pages which link to a page
containing term Subdue

• Subgraph vertices
•  
• 1 page
• URL http//cygnus.uta.edu
• 7  page
• URL http//cygnus.uta.edu/projects.html
• Subdue
• 1-gt7 hyperlink
• 7-gt8 word

Subdue

word
hyperlink
page
page
/ Vertex ID Label / s v 1 page v 2 page v
3 Subdue
/ Edge Vertex 1 Vertex 2 Label / d 1 2
hyperlink d 2 3 word
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Search for Presentation Pages
page
hyperlink
hyperlink
hyperlink
page
page
page
hyperlink
hyperlink

• WebSubdue
• 22 instances

• AltaVista
• Query hostwww-cse.uta.edu AND
  imagenext_motif.gif AND imageup_motif.gif AND
  imageprevious_motif.gif.
• 12 instances

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Search for Reference Pages
page
hyperlink
hyperlink
hyperlink

page
page
page

• Search for page with at least 35 in links
• WebSubdue found 5 pages in www-cse
• AltaVista cannot perform this type of search

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Inclusion of WordNet

• When generating graph
• Use common stopword list
• When searching for subgraph instances
• Morphology functions
• October Oct
• teaching teach
• Synsets
• Optional allowance of synonyms

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Search for pages on jobs in computer science

• Inexact match allow one level of synonyms
• WebSubdue found 33 matches
• Words include employment, work, job, problem,
  task
• AltaVista found 2 matches

page
word
word
word
jobs
computer
science
14
Search for authority hub and authority pages

• WebSubdue found 3 hub (and 3 authority) pages
• AltaVista cannot perform this type of search

• Inexact match applied with threshold 0.2 (4.2
  transformations allowed)
• WebSubdue found 13 matches

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Subdue Learning from Web Data

• Distinguish professors and students web pages
• Learned concept (professors have box in address
  field)
• Distinguish online stores and professors web
  pages
• Learned concept (stores have more levels in graph)

page
page
page
page
page
page
page
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Conclusions

• WebSubdue can be used to search for structural
  web data
• Could be enhanced with additional WordNet
  features such as synset path length
• Efficient structural search necessary for future
  of web search tools

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To Learn More
cygnus.uta.edu/subdue
cook_at_cse.uta.edu http//www-cse.uta.edu/cook