Document Ontology Extractor (DOE) Research Team: Govind R Maddi, Jun Zhao Chakravarthi S Velvadapu Faculty: Dr.Sadanand Srivastava Dr.James Gil De Lamadrid Joint Project of University of Maryland, Baltimore County Bowie State University Sponsored

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Document Ontology Extractor(DOE)Research
TeamGovind R Maddi, Jun Zhao Chakravarthi S
VelvadapuFacultyDr.Sadanand
SrivastavaDr.James Gil De LamadridJoint
Project of University of Maryland, Baltimore
CountyBowie State UniversitySponsored
byDepartment Of Defense
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OVERVIEW

1. The system takes text documents as its input
2. Performs semantic analysis on these documents
3. Generates useful ontology
4. Represents it graphically

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GOAL

• To build an Ontology utilizing
• Statistical methods
• A small amount of user feedback
• Automation

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Architecture of DOE
Text Document
Pre-processing
Normalization
Latent Semantic Indexing (SVD)
Document Ontology
Graph Construction
GUI
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INPUT

• Text documents

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Pre-processing

• Read-in text file
• Extract meaningful terms
• Count their frequencies

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Normalization

• Calculate weight of each term using
• W i,k frequency i,k nk
• S frequency j,k

• Calculate weight of each term using
• W i,k frequency i,k nk
• S frequency j,k
• j1

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Normalization(contd)

• Calculate normalized weight using
• W i,k w(i,k)
• nk
• sqrt(S w2(j,k))
• j1

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Latent Semantic Indexing(LSI)

• Statistical method representing documents by
  statistically independent concepts
• Based on Singular Value Decomposition (SVD)

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Singular Value Decomposition (SVD)

• A technique that decomposes a given matrix into
  three components U, S and V.

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SVD (contd)

• m x n term-document matrix A, of rank r, can be
  expressed as the product
• A U S VT
• U is m x r term matrix
• S is r x r diagonal matrix
• V is r x n document matrix

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SVD (contd)

• Diagonal of S contains singular values of A in
  the descending order.

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SVD (contd)

• A is formed from LSI as follows
• A US SS VsT
• US - derived from U removing all but the s
  columns
• SS - derived from S removing all but the largest
  s singular values
• VsT - derived from VT removing all but the s
  corresponding rows

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SVD (contd)

US
VsT
SS
A m x n
U m x r
S r x r
VT r x n
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Document Ontology

• Build Concept Nodes and Term Nodes
• using the document matrix (V) and term
  matrix (U).

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Building concept nodes from term matrix(U)

• A concept node contains information about
• Concept name
• Terms that belong to that concept
• Respective weights of terms in that concept

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Building concept nodes from term matrix(U) (contd)

• Naming convention
• Generates automatically
• A hyphenated string of the five most high
  frequent terms in that concept

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Building concept nodes from term matrix(U) (contd)

• A concept node represents a document
• Each column in U corresponds to a concept node

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Building term nodes from term matrix(U)

• A term node contains information about
• Term name
• Concepts to which it belongs
• Its respective weight in each concept

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Building term nodes from term matrix(U) (contd)

• Naming convention
• Generates automatically
• Simply named using the term name

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Building term nodes from term matrix(U) (contd)

• A term node represents a term
• Each row in U corresponds to a term node

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Graph Construction

• A bipartite graph is constructed with concept
  nodes and term nodes
• A concept node is connected to all term nodes
  that belong to it.
• A term node is connected to all concept nodes to
  which it belongs.

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Graph Construction (contd)
Term 1
Concept 1
Term 2
Term 3
Term 4
Concept 2
Term 5
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Graphical User Interface

• (GUI)

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GUI (contd)

• GUI consists of
• Concepts list
• Terms list
• Display for bipartite graph
• Display for list of files in ontology

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GUI

• To view terms related to a concept, user selects
  that concept from concepts list
• To view concepts related to a term, user selects
  that term from terms list

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GUI (contd)

• To view only terms related to a specific concept
• Select that concept from concepts list
• Select checkbox Display Selected Ones Only
• Result
• GUI displays ONLY relations between selected
  terms and concepts

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GUI (contd)

• To view only concepts related to a term
• Select that term from terms list
• Select checkbox Display Selected Ones Only
• Result
• GUI displays ONLY relations between selected
  terms and concepts

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GUI (contd)

• To highlight relationship between a term and a
  concept
• Select that term or concept from terms or
  concepts list
• Click on line connecting term and concept

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GUI File Operations

• New
• Open
• Save

• saveAs
• Close
• Exit

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GUI Ontology Updates

• Add
• Delete
• ChangeSVDThreshold
• changeConcThreshold
• foldInDoc
• defaultBuild

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GUI Ontology Updates

• Add
• Click on Add
• Select file to be added from file chooser popup
  menu
• Choose whether to build now or not
• If yes document is added and displayed
• If no GUI remains unchanged

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GUI Ontology Updates

• Delete
• Click on Delete
• Select file to be deleted from file chooser popup
  menu
• Choose whether to build now or not
• If yes document is deleted and displayed
• If no GUI remains unchanged

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GUI Ontology Updates

• changeSVDThreshold
• SVDThreshold controls the largest s singular
  values that will be selected from S.
• Default value is 70 i.e. only the singular
  values higher than 70 of the highest singular
  value are selected
• User can change this default value

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GUI Ontology Updates

• changeConcThreshold
• Controls the number of terms related to a concept
  based upon term weight
• Default value is 70 i.e. only the terms with
  weights higher than 70 of the highest term
  weight are selected
• User can change this default value

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GUI Ontology Modifications

• Rename
• Renames a selected concept
• DelTerm
• Deletes a selected term
• Undo
• Ignores last modification and returns to the
  previous state

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Future Work

• To investigate less expensive methods for adding
  new documents
• Fold-In
• SVD update

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Future Work

• Fold-In
• A method to add new document(s) to an existing
  ontology
• Uses the existing data in document addition
  process
• Less expensive process than the regular build
  method

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Acknowledgements

• We express our appreciation to
• Department Of Defense
• University of Maryland, Baltimore County
• Advisors, Bowie State University