Consistency, Acyclicity, and Positive Semirings
summary
Shows that for positive semiring K annotated relations, every pairwise-consistent family has a global witness exactly when the schema forms an acyclic hypergraph; this unifies Beeri–Fagin–Maier–Yannakakis and Vorob'ev by replacing equality with an equivalence by scaling of K-relations. Proofs use a nontrivial join/normalization, a reduction to minimal nonconformal or nonchordal subhypergraphs, and explicit Tseitin-style constructions of K-relations that are pairwise but not globally consistent. Special cases recover Boolean and probability results; extensions to positive monoids give strict-consistency characterizations and exhibit counterexamples (even for a path).
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chapters (6)
- 0:00Local and global consistency
- 3:58Database theory and BFMY theorem
- 18:59K-relations with positive semirings
- 27:50Vorob'ev and BFMY theorems unified
- 31:46Positive monoids work
- 32:07Q&A
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