Database Systems (TODS)


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ACM Transactions on Database Systems (TODS), Volume 15 Issue 4, Dec. 1990

Concepts and effectiveness of the cover-coefficient-based clustering methodology for text databases
Fazli Can, Esen A. Ozkarahan
Pages: 483-517
DOI: 10.1145/99935.99938
A new algorithm for document clustering is introduced. The base concept of the algorithm, the cover coefficient (CC) concept, provides a means of estimating the number of clusters within a document database and related indexing and clustering...

Translation with optimization from relational calculus to relational algebra having aggregate functions
Ryohei Nakano
Pages: 518-557
DOI: 10.1145/99935.99943
Most of the previous translations of relational calculus to relational algebra aimed at proving that the two languages have the equivalent expressive power, thereby generating very complicated relational algebra expressions, especially when...

A compression technique to materialize transitive closure
H. V. Jagadish
Pages: 558-598
DOI: 10.1145/99935.99944
An important feature of database support for expert systems is the ability of the database to answer queries regarding the existence of a path from one node to another in the directed graph underlying some database relation. Given just the...

A parallel algorithm for record clustering
Edward Omiecinski, Peter Scheuermann
Pages: 599-624
DOI: 10.1145/99935.99947
We present an efficient heuristic algorithm for record clustering that can run on a SIMD machine. We introduce the P-tree, and its associated numbering scheme, which in the split phase allows each processor independently to compute the unique...

The hB-tree: a multiattribute indexing method with good guaranteed performance
David B. Lomet, Betty Salzberg
Pages: 625-658
DOI: 10.1145/99935.99949
A new multiattribute index structure called the hB-tree is introduced. It is derived from the K-D-B-tree of Robinson [15] but has additional desirable properties. The hB-tree internode search and growth processes are precisely analogous to the...