2 research outputs found
c-Perfect Hashing Schemes for Binary Trees, with Applications to Parallel Memories
We study the problem of mapping tree-structured data to an
ensemble of parallel memory modules. We are given a “conflict tolerance”
c, and we seek the smallest ensemble that will allow us to store any nvertex rooted binary tree with no more than c tree-vertices stored on the
same module. Our attack on this problem abstracts it to a search for the
smallest c-perfect universal graph for complete binary trees. We construct
such a graph which witnesses that only O
¡
c
(1¡1=c)
¢ 2
(n+1)=(c+1)
¢
memory modules are needed to obtain the required bound on conflicts, and
we prove that
¡
2
(n+1)=(c+1)
¢
memory modules are necessary. These
bounds are tight to within constant factors when c is fixed—as it is with
the motivating application