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Structure of IR Systems

This module explores the nature of Information Retrieval (IR) systems, their functions, and the structure of interactive IR systems. It covers different types of information needs, queries, and document representations. It also discusses relevance, utility, and pertinence in the context of IR. Additionally, it compares databases and IR systems in terms of content, queries, and results.

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Structure of IR Systems

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  1. Structure of IR Systems INST 734 Module 1 Doug Oard

  2. Segments • The nature of Information Retrieval (IR) • What IR systemsdo • The structure of interactive IR systems

  3. Systems: The Memex

  4. Types of Information Needs • Retrospective (“Retrieval”) • “Searching the past” • Different queries posed against a static collection • Prospective (“Recommendation”) • “Searching the future” • Static query posed against a dynamic collection

  5. Controlled Vocabulary Searcher Free-Text Searcher Indexer Choose appropriate concept descriptors Construct query from available concept descriptors Construct query from terms that may appear in documents Content-Based Query-Document Matching Metadata-Based Query-Document Matching Query Terms Document Terms Document Descriptors Query Descriptors Retrieval Status Value Two Ways of Searching Author Write the document using terms to convey meaning

  6. The IR Black Box Documents Query Hits

  7. Inside the IR Black Box Documents Query Representation Function Representation Function Query Representation Document Representation Index Comparison Function Hits

  8. Utility Human Judgment Information Need Document Query Formulation Query Document Processing Query Processing Representation Function Representation Function Query Representation Document Representation Comparison Function Retrieval Status Value

  9. Relevance • Relevance relates a topic and a document • Duplicates are equally relevant, by definition • Constant over time and across users • Pertinence relates a task and a document • Accounts for quality, complexity, language, … • Utility relates a user and a document • Accounts for prior knowledge

  10. 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 Unambiguous formally (mathematically) defined queries. Vague, imprecisequeries (and information needs) Results we get Exact. Always correct in a formal sense. Sometimes relevant, often not. Interaction with system Single query produces a complete answer. Interaction sequence can help resolve vagueness. Nature of the content Able to handle real-time updates. Updates can often be processed offline. Comparing Databases andIR

  11. Segments • The nature of Information Retrieval (IR) • What IR systemsdo • The structure of interactive IR systems

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