AWhat changed
Hashed-bit occupancy and stochastic averaging estimate distinct cardinalities in one pass with small mergeable bitmap summaries, supported by asymptotic analysis under an independent uniform-hash model.
Scientific scope
Hashed-bit occupancy and stochastic averaging estimate distinct cardinalities in one pass with small mergeable bitmap summaries, supported by asymptotic analysis under an independent uniform-hash model. This records the 1983 method family through the expanded 1985 paper. PCSA uses approximately uniform hash bits and stochastic averaging; its roughly 0.78/sqrt(m) relative error is a typical asymptotic standard error, not a deterministic promise for every input. Compatible bitmaps can be merged by bitwise OR, but this does not provide deletion. Small-cardinality corrections and implementation/hash assumptions matter. Results stated only in the expanded 1985 text are not assigned to the unread 1983 preliminary paper. WRS has not independently reconstructed the complete analytic proof or replayed the reported experiments.
Evidence
Source-linked, scoped account of the original work. The published scope states the scientific assumptions and remaining verification limits. WRS has not independently certified the full proof, experimental result or system benchmark.
Contributors
- Philippe Flajolet; G. Nigel Martin · SCIENCE: Completeoriginal2byline;1983preliminary/1985expandedfamily.
- Morris; earlier hashing and Mellin-analysis contributors · SCIENCE: Explicitly credited antecedents, distinct from this paper's coauthors.
- Kyu Young Wang; M. Schkolnick; R. Fagin; IBM host laboratories · INFRASTRUCTURE: Source-named implementation, support, discussions and visits; additional byline credit or effort percentages are not inferred.
Provisional WRS assessment, edition 2026-10-16.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.
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