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The Logic of Counting Query Answers

Talkat Symmetry, Logic, Computation 2016 · 2016-11-07..11-10· [databases]
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A logic called sharp logic is defined that outputs a numeric value for a formula on a finite structure and supports casting first‑order formulas, projection, multiplication, addition and integer constants; bounded width evaluation runs in polynomial time. A dichotomy is proved for existential positive queries: fixed‑parameter tractability holds iff the query compiles to a bounded‑width sharp logic representation. An algorithm uses inclusion–exclusion to normalize, applies width minimization (computable), and relies on an independence theorem showing linear independence of homomorphism‑count vectors.

AI-written summary · about

  1. 0:00Intro
  2. 0:28Query evaluation
  3. 3:15Studying complexity
  4. 5:33Parameterized complexity
  5. 7:13Classification
  6. 17:12Example
  7. 18:56Width minimization
  8. 24:23Open issues
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