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Semantic Network Complexity And Metathesaurus Maintenance

Explore the challenges and problems related to the complexity and maintenance of the Semantic Network Metathesaurus. Discover the structures, limited use, and problematic assignments within the network. Learn about the formalization gap, duality of central notions, boundary phenomenon, and Nelson's Lemma. Understand practical considerations for achieving consistency, managing changes, and distributing assignments. Gain insights into understanding source meanings, maintaining consistency, and respecting the meaning in the source.

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Semantic Network Complexity And Metathesaurus Maintenance

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  1. Semantic Network ComplexityAnd Metathesaurus Maintenance Stuart Nelson, MD “Dr. Ad Hoc”

  2. Role of Semantic Network • Categorize the Concepts of the Metathesaurus • Model Reality • Model the Contents

  3. Semantic Network Problems • Structural Considerations • Limited Use • Poor Type Assignments

  4. Problematic Assignments • Inconsistent Assignments • “Wrong” Assignments • Strange Type Co-Occurrences

  5. Why Do These Things Happen” • Stupid Editors? • Poor Selection of Types? • Inherent Complexity? • Poor Management

  6. Where Does Complexity Arise, Or Why Is This So Hard? • Formalization Gap • Duality of Central Notions • Boundary Phenomenon • Nelson’s Lemma

  7. Formalization Gap Natural Language Understanding Pattern Recognition Recall and Reliable Memory Formal Reasoning Formalization Gap

  8. A Different Aspect • Humans Have Difficulty With Formal Notions • Formal Definitions • A set of ordered pairs • The set of first coordinates of the ordered pairs

  9. Duality of Central Notions • Cancer – Process or Object? • Gene – Locus or Sequence? • Finding - Event or Relationship? • Waves and Particles

  10. Boundary Phenomenon • Definitional Characteristics • Necessary and Sufficient Attributes

  11. Nelson’s Lemma • Greater Number of Boundaries LEADS TO • Greater Number of Borderline Cases • Overlapping “Extents”

  12. Process of Semantic Type Assignment • Default Assignment from Source • Some Sources (MeSH) have STYs • Human Review of Concept Status • Human Review of Semantic Types

  13. Practical Considerations • Achieving Consistency • Managing Changes • Distribution of STY Assignments • Understanding Source Meanings • URU Criteria

  14. Achieving Consistency • See Nelson’s Lemma • Internal (Self) Consistency • Editorial Variability • Inconsistent Rules • Use Parent • Use Several Children

  15. Managing Changes • How Many Seconds per Change? • How Many Records to Edit? • What Can Be Done Algorithmically? • Resources Available

  16. Distribution of Assignments • Overlapping Meanings • Facet-Based Typing • Inconsistent Rules

  17. Understanding Source Meanings • Definitions Rare • “Contextual Understanding” • Hierarchies • Most Vocabularies A Set of Engineering Compromises

  18. Prime Directive • Respect the Meaning in the Source • Names Lack Face Validity • Reification of Relationships

  19. Respect • Reality - Names and Rules Only Reflect Our Understanding • Sources - Reflect The View of The Source

  20. URU Criteria For Types • Understandable • Reproducible • Usable

  21. Challenges • Analysis • Useful algorithms • Time Involved • Assessing Benefit • Training • Establishing Business Rules • Testing Consistency

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