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CS255 Fundamentals of Information Retrieval

Lecture 1 Introduction to Information Retrieval

Krishnendu Ghosh

Department of Computer Science & Engineering

Indian Institute of Information Technology Dharwad

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Information Retrieval (IR)

Information Retrieval (IR) is finding material (usually documents) of an unstructured nature (usually text) that satisfies an information need from within large collections (usually stored on computers).

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These days we frequently think first of web search, but there are many other cases:

  1. E-mail search
  2. Searching your laptop
  3. Corporate knowledge bases
  4. Legal information retrieval

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Text: Unstructured vs Structured (Mid-90s)

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Text: Unstructured vs Structured (2000s)

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Information Retrieval: Why?

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Information Retrieval: Why?

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Information Retrieval: Why not RDBMS?

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Information Retrieval: Transform

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Information Retrieval: Core Concepts

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Information Retrieval: Core Concepts

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Information Retrieval: Applications

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IR Applications: Text Categorization

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IR Applications: Text Categorization

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IR Applications: Text Categorization

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IR Applications: Document Clustering

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IR Applications: Content Based Filtering

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IR Applications: Collaborative Filtering

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IR Applications: Information Extraction

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IR Applications: Question Answering

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IR Applications: Web Search

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IR Applications: Federated Search

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IR Applications: Expertise Search

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IR Applications: Citation/Link Analysis

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IR Applications: Citation/Link Analysis

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IR Applications: Multimedia Retrieval

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IR Applications: Information Visualization

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Basic Assumptions of Information Retrieval

  • Collection: A set of documents
    • Assume it is a static collection for the moment

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  • Goal: Retrieve documents with information that is relevant to the user’s information need and helps the user complete a task

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Classic Search Model

Query

Search Engine

Query

Reformulation

Repository

Result

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How Good are the Retrieval System?

  • Precision: Fraction of retrieved docs that are relevant to the user’s information need
  • Recall: Fraction of relevant docs in collection that are retrieved

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More precise definitions and measurements to follow later

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Quiz 1

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Thank You