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Web- and Multimedia-based Information Systems. Assessment Presentation Programming Assignment.

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Presentation on theme: "Web- and Multimedia-based Information Systems. Assessment Presentation Programming Assignment."— Presentation transcript:

1 Web- and Multimedia-based Information Systems

2 Assessment Presentation Programming Assignment

3 Presentations Document Management Systems & OCR – Market Overview – Algorithm Introduction Video on Demand – Real Media – Technology Authoring Systems – Macromedia Products

4 Presentations Content Management – Functionality – Market Overview – Opencms Application Server – Functionality – Market Overview

5 Presentations VRML – Syntax Introduction – Exercise SMIL : Multimedia Synchronisation – Syntax Introduction – Exercise

6 Presentations Software / Frontend Ergonomics (HCI) Usability Navigation

7 What are Information Systems? Store Information Retrieval

8 Information Textual Audiovisual – Images – Audio – Video Multimedia Documents

9 Information System Classification Expert Systems Transaction Processing Systems Office Automation Systems Management/Executive Information Systems Geographic Information Systems Information Retrieval Systems

10 Expert Systems Problem Solving Artificial Intelligence Replace an Expert Multiple operational Implementations Often Implemented using Prolog

11 Transaction Processing Systems Records Events of interest to an organization Supports the operational level of the business High data volume

12 TPS applications Manufactoring and Production Sales and Marketing Finance and Accounting Human Resources

13 Office Automation Personal Productivity Groupware & Communications

14 Management/Executive Information Systems Analysis of TPS data Higher Level Reports Drill Down to detailed Information possible

15 Geographic Information Systems Different Sources Spatial Data Visualization

16 Information Retrieval

17 Information Retrieval System Manages Documents = Records of Information Presents relevant Documents on a Query

18 Information Retrieval System Examples POTS directory assistance Library Catalog World Wide Web Search Engine

19 Information Retrieval Deals with the – Representation of – Storage of – Organization of – Access to Information items

20 History Early Example: Book‘s Table of Contents Indices in libraries Only recently automatic indexing The Web – Easy & cheap access – Variety of sources – Freedom of Publication, Interactivity

21 Data Retrieval vs Information Retrieval Exact match Looks for matching items Complete Query Data with well defined structure and semantics Best match Looks for Relevant Items Incomplete Query Natural Language Documents

22 Information Retrieval and the Web IR originally Text Indexing and Searching Web is highly heterogenous System, no common data model Navigation is ineffiecient Information Retrieval promises to structure information and ease fulfilling information needs

23 Usage: Information Retrieval User has Information need User translates this need into a machine- understandable Query System retrieves relevant Information

24 The User Retrieval Browsing Database

25 Logical Views of a Document Full text Set of Index Terms – Specified by human expert – Text Operations Elimination of Stopwords Stemming Compression Intermediate Logical Views Structure Recognition

26 Retrieval Process User Interface Text Operations Text Database DB Manager Module Index Searching Ranking

27 Operational Modes Ad Hoc – Fixed Database, changing Queries Filtering – Fixed Queries, changing Database – User Profiles

28 Information Retrieval Data Structures

29 Data Structures Linear list Sequentially ordered file Indexed file

30 Linear List Unsorted list of documents Easy addition of files Traversal required for a search Author D Author E Author A Author F 1 2 3 4 5 6 7 Author B Author G Author C

31 Sequentially Ordered File Sorted by the values of a Key Addition of documents more involved Binary search possible Author A Author B Author C Author D 1 2 3 4 5 6 7 Author E Author F Author G

32 Indices A1B2...F6A1B2...F6 Author A Author B Author C Author D 1 2 3 4 5 6 Author E Author F

33 Inverted Indices An index of all the words in the texts Vocabulary – Different Words in the text – Little Space required after Text Operations Occurences – Positions – More Space required, ~30-40% of text size

34 Inverted Indices Block Addressing – Smaller Pointers – References in one block are collapsed – Online Search required for exact positions – Fixed Size Blocks or Natural Cuts Fully Inverted Indices – For less readily accessable collections if exact position is required

35 Information Retrieval Models

36 Classic IR Models Boolean Vector Probabilistic

37 Common Concepts Index Terms Weigths for varying relevance

38 Boolean Model Pro Easy to understand Precise Semantics of a query Contra Binary Decision Difficult for users

39 Boolean Model Example Query Q = 1 AND ( 2 OR NOT 3) AND 1 OR 2NOT 3

40 Boolean Model – Set Operations AND : Intersection (Durchschnitt) OR : Union (Vereinigung) NOT : Complement (Komplement) – Seldom used on its own

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