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Ontology Builder: Semantic Analysis and Graphical Representation

This system performs semantic analysis on text documents, generates an ontology, and represents it graphically. It utilizes statistical methods, user feedback, and automation.

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Ontology Builder: Semantic Analysis and Graphical Representation

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  1. Document Ontology Extractor(DOE)Research Team:Govind R Maddi, Jun Zhao Chakravarthi S VelvadapuFaculty:Dr.Sadanand SrivastavaDr.James Gil De LamadridJoint Project ofUniversity of Maryland, Baltimore CountyBowie State UniversitySponsored byDepartment Of Defense

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

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

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

  5. INPUT Text documents

  6. Pre-processing • Read-in text file • Extract meaningful terms • Count their frequencies

  7. Normalization • Calculate weight of each term using • W i,k = frequency i,knk • Σfrequency j,k • Calculate weight of each term using W i,k = frequency i,knk Σfrequency j,k j=1

  8. Normalization(contd) • Calculate normalized weight using W i,k w(i,k) nk sqrt(Σ w2(j,k)) j=1

  9. Latent Semantic Indexing(LSI) • Statistical method representing documents by statistically independent concepts • Based on Singular Value Decomposition (SVD)

  10. Singular Value Decomposition (SVD) • A technique that decomposes a given matrix into three components – U, S and V.

  11. 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

  12. SVD (contd) • Diagonal of S contains singular values of A in the descending order.

  13. 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

  14. SVD (contd) US SS VsT A m x n U m x r S r x r VT r x n

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

  16. 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

  17. 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

  18. Building concept nodes from term matrix(U) (contd) • A concept node represents a document • Each column in U corresponds to a concept node

  19. 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

  20. Building term nodes from term matrix(U) (contd) • Naming convention: • Generates automatically • Simply named using the term name

  21. Building term nodes from term matrix(U) (contd) • A term node represents a term • Each row in U corresponds to a term node

  22. 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.

  23. Graph Construction (contd) Term 1 Concept 1 Term 2 Term 3 Term 4 Concept 2 Term 5

  24. Graphical User Interface (GUI)

  25. GUI (contd) • GUI consists of • Concepts list • Terms list • Display for bipartite graph • Display for list of files in ontology

  26. 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

  27. 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

  28. 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

  29. 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

  30. New Open Save saveAs Close Exit GUI – File Operations

  31. GUI – Ontology Updates • Add • Delete • ChangeSVDThreshold • changeConcThreshold • foldInDoc • defaultBuild

  32. 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

  33. 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

  34. 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

  35. 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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