We present new hash tables for joins, and a hash join based on them, that consumes far less memory and is usually faster than recently published in-memory joins. Our hash join is not restricted to outer tables that fit wholly in memory. Key to this hash join is a new concise hash table (CHT), a linear probing hash table that has 100% fill factor, and uses a sparse bitmap with embedded populatio...

It is well known that finite commutative association schemes in the sense of the monograph of Bannai and Ito lead to finite commutative hypergroups with positive dual convolutions and even dual hypergroup structures. In this paper we present several discrete generalizations of association schemes which also lead to associated hypergroups. We show that discrete commutative hypergroups associated...

Hypergroups are generalizations of groups. If this binary operation is taken to be multivalued, then we arrive at a hypergroup. The motivation for generalization of the notion of group resulted naturally from various problems in non-commutative algebra, another motivation for such an investigation came from geometry. In various branches of mathematics we encounter important examples of topologi...

This paper presents Plug&Join, a new generic algorithm for efficiently processing a broad class of different types of joins in an extensible database system. Plug&Join is not only designed to support equi joins, temporal joins, spatial joins, subset joins and other types of joins, but in contrast to previous algorithms it can be easily customized and it allows efficient processing of new types ...

In this paper, we give an extension of the Wendel's theorem on KPC-hypergroups. We also show that every translation invariant mapping is corresponding with a unique positive measure on the KPC-hypergroup.

In this paper we introduce the notions of fuzzy transposition hypergroupsand fuzzy regular relations and investigate their basic properties.We also study fuzzy quotient hypergroups of a fuzzy transposition hypergroup.