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Information Retrieval & Pattern Recognition

Information Retrieval & Pattern Recognition. Dr. R. J. Ramteke Associate Professor, Dept. of Computer Science North Maharashtra University, Jalgaon. Agenda . Information What is “information”? Retrieval What do we mean by “retrieval”? What are different types information needed? Systems

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Information Retrieval & Pattern Recognition

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  1. Information Retrieval & Pattern Recognition • Dr. R. J. Ramteke • Associate Professor, • Dept. of Computer Science • North Maharashtra University, Jalgaon

  2. Agenda • Information • What is “information”? • Retrieval • What do we mean by “retrieval”? • What are different types information needed? • Systems • How do computer systems fit into the human information seeking process? • Pattern Recognition

  3. What is Information? • What do you think? • There is no “correct” definition • Cookie Monster’s definition: • “news or facts about something” • Different approaches: • Philosophy • Psychology • Linguistics • Electrical engineering • Physics • Computer science • Information science

  4. Dictionary says… • Oxford English Dictionary • information: informing, telling, knowledge, items of knowledge, news • knowledge: knowing, familiarity gained by experience; person’s range of information; a theoretical or practical understanding of; the sum of what is known • Random House Dictionary • information: knowledge communicated or received concerning a particular fact or circumstance; news

  5. Intuitive Notions • Information must • Be something, although the exact nature (substance, energy, or abstract concept) is not clear; • Be “new”: repetition of previously received messages is not informative • Be “true”: false or counterfactual information is “mis-information” • Be “about” something • Three Views of Information • Information as process • Information as communication • Information as message transmission and reception Robert M. Losee. (1997) A Discipline Independent Definition of Information. Journal of the American Society for Information Science, 48(3), 254-269.

  6. One View • Information = characteristics of the output of a process • Tells us something about the process and the input • Information-generating process do not occur in isolation Input Output Process Input Output Input Output Process1 Process2 Input Output … Ibid.

  7. Another View • Information science is characterized by “the deliberate (purposeful) structure of the message by the sender in order to affect the image structure of the recipient” • This implies that the sender has knowledge of the recipient's structure • Text = “a collection of signs purposefully structured by a sender with the intention of changing image-structure of a recipient” • Information = “the structure of any text which is capable of changing the image-structure of a recipient” Nicholas J. Belkin and Stephen E. Robertson. (1976) Information Science and the Phenomenon of Information. Journal of the American Society for Information Science, 27(4), 197-204.

  8. Transfer of Information • Communication = transmission of information Thoughts Thoughts Telepathy? Words Words Writing Sounds Sounds Speech Encoding Decoding

  9. Information Theory • Better called “communication theory” • Developed by Claude Shannon in 1940’s • Concerned with the transmission of electrical signals over wires • How do we send information quickly and reliably? • Underlies modern electronic communication: • Voice and data traffic… • Over copper, fiber optic, wireless, etc. • Famous result: Channel Capacity Theorem • Formal measure of information in terms of entropy • Information = “reduction in surprise”

  10. Transmitter channel Receiver message noise The Noisy Channel Model • Communication = producing the same message at the destination that was sent at the source • The message must be encoded for transmission across a medium (called channel) • But the channel is noisy and can distort the message • Semantics (meaning) is irrelevant Source Destination message

  11. More refined and abstract Wisdom Knowledge Information Data Information Hierarchy

  12. Information Hierarchy • Data • The raw material of information • EX - 98.6º F, 99.5º F, 100.3º F, 101º F, … • Information • Data organized and presented in a particular manner • EX - Body temperature: 98.6º F, 99.5º F, 100.3º F… • Knowledge • Information that can be acted upon • EX - If you have a temperature above 100º F, you most likely have a fever • Wisdom • Distilled and integrated knowledge • Demonstrative of high-level “understanding” • EX - If you don’t feel well, go see a doctor

  13. Encoding Decoding storage “Retrieval?” • “Fetch something” that’s been stored • Recover a stored state of knowledge • Search through stored messages to find some messages relevant to the task at hand Sender Recipient message message indexing/writing Retrieval/reading noise

  14. What is IR? • Information retrieval is a problem-oriented discipline, concerned with the problem of the effective and efficient transfer of desired information between human generator and human user • Types of Information Needs • Retrospective • “Searching the past” • Different queries posed against a static collection • Time invariant • Prospective • “Searching the future” • Static query posed against a dynamic collection • Time dependent Anomalous States of Knowledge as a Basis for Information Retrieval. (1980) Nicholas J. Belkin. Canadian Journal of Information Science, 5, 133-143.

  15. Retrospective Searches • Ad hoc retrieval: find documents “about this” • Known item search • Directed exploration Compile a list of mammals in Gondwana region, that are considered to be endangered, identify their habits and, if possible, specify what threatens them. Find BAMU homepage. What’s the ISBN number of “Modern Information Retrieval”? Who makes the best chocolates? Which is the affordable makes of Washing Machine?

  16. Prospective “Searches” • Filtering • Make a binary decision about each incoming document • Routing • Sort incoming documents into different bins? Spam or not spam? Categorize news headlines: World? Nation? Metro? Sports?

  17. What types of information? • Text (Documents and portions thereof) • XML and structured documents • Images • Audio (sound effects, songs, etc.) • Video • Source code • Applications/Web services

  18. What about databases? • What are examples of databases? • Banks storing account information • Retailers storing inventories • Universities storing student grades • What exactly is a (relational) database? • Think of them as a collection of tables • They model some aspect of “the world”

  19. A (Simple) Database Example Student Table Department Table Course Table Enrollment Table

  20. Databases IR What we’re retrieving Structured data. Clear semantics based on a formal model. Mostly unstructured. Free text with some metadata. Queries we’re posing Formally (mathematically) defined queries. Unambiguous. Vague, imprecise information needs (often expressed in natural language). Results we get Exact. Always correct in a formal sense. Sometimes relevant, often not. Interaction with system One-shot queries. Interaction is important. Other issues Concurrency, recovery, atomicity are all critical. Issues downplayed. Databases vs. IR

  21. Resource Query Ranked List Documents query reformulation, vocabulary learning, relevance feedback Documents source reselection The Information Retrieval Cycle Source Selection Query Formulation Search Selection Examination Delivery

  22. Taylor’s Model • The visceral need (Q1) the actual, but unexpressed, need for information • The conscious need (Q2) the conscious within-brain description of the need • The formalized need (Q3) the formal statement of the question • The compromised need (Q4) the question as presented to the information system Robert S. Taylor. (1962) The Process of Asking Questions. American Documentation, 13(4), 391--396.

  23. The Central Problem in IR Information Seeker Authors Query Terms Document Terms Do these represent the same concepts? Pattern Recognition …

  24. Pattern Recognition • Pattern : A Visible Entity • Recognition = Re+ Cognition • Learning • < Re-Enforcement of • Learning > • Labelling

  25. Pattern Recognition:An Overview • Pattern recognition is characteristics to all living organisms, however, creatures recognize differently • We have many ways to recognize the given patterns • Human by sight, voice (sound recognition), walking style (tracking), his vehicle (context based ) etc, • Dog recognizes a human or animal by smelling • Blind person recognizes the objects by touching

  26. Pattern Recognition:An Overview • Pattern – the object which is inspected for the recognition process is called a pattern • Usually we refer to pattern as a description of an object which we want to recognize • Pattern recognition problem is a problem of discriminating between different populations • Eg. Tall and Thin, Tall and Fat, Short and Thin, and Short and Fat • Recognition process thus, turns into classification (if we consider the age as feature and height and weight as a features)

  27. Pattern Recognition:An Overview • Pattern recognition system should be able to obtain an unknown incoming pattern and classify it in one (or more) of several given classes . • The goal of PR is classification of patterns Eg. Decision function • d(x) > 0 x belong to C1 and d(x) < 0 x belong to C2 • where d(x) = 0 is hyper plane is called decision boundary and C1 and C2 are two classes.

  28. Pattern Recognition Techniques to classify or describe What : Samples/Objects/Patterns How : By means of the measured properties called features. Thus, PR Data Acquisition + Data Analysis

  29. The major approaches to PR are • The Statistical PR approach • Syntactic PR approach and • Neural network has provided as third approach • Types of Patterns: • Spatial patterns (patterns are located in space) • Characters in character recognition . • Temporal patterns( Distributed in time ) • Speech Recognition • Abstract patterns (patterns are distributed neither in space nor time) • Classification of people based on psychological tests.

  30. Applications of Pattern Recognition • Object Recognition • Document Image Processing • Content Based Image Retrieval • Image Mosaicing • Character /Numeral Recognition • Face Recognition • Finger Print Identification • Medical Diagnosis • Signature Verification • Industrial Inspection • Video Indexing • Robot Manipulation • Computer Vision

  31. If the Patterns are Pictures/ images, then the PR stages are : • Image Acquisition • Image Enhancement • Image Segmentation • Image Feature Extraction • Image Matching

  32. Stages in Pattern Recognition • Delineation Feature Extraction Descriptive features Discriminatingfeatures • Representation • Classification

  33. Feature Extraction : Feature : An extractable measurement. Why ? : For Description. What Feature ? : Depends on purpose of classification. How many ? : Depends on Qualities of the PR System. When ? : 1. Cognition 2. Recognition How ? : ??!!!

  34. Examples (1) : Feature Extraction Objects : A B C D E F

  35. Feature? Line and Curve Segments

  36. Knowledge Acquired

  37. Machine Learning through Vision? Re Learning A COW A COW WITH THREE LEGS AND TWO TAILS

  38. Thank you one and all Dr. R. J. Ramteke rakeshramteke@yahoo.co.in 9890688672

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