Title
On the decisional complexity of problems over the reals
Abstract
We consider the role of randomness for the decisional complexity in algebraic decision (or computation) trees, i.e., the number of comparisons ignoring all other computation. Recently Ting and Yao showed that the problem of finding the maximum of n elements has decisional complexity O (log2 n) (1994, Inform. Process. Lett., 49, 39-43). In contrast, Rabin showed in 1972 an &Ohgr;(n) bound for the deterministic case (1972, J. Comput. System Sci., 6, 639-650). We point out that their technique is applicable to several problems for which corresponding &Ohgr;(n) lower bounds hold. We show that in general the randomized decisional complexity is logarithmic in the size of the decision tree. We then turn to the question of the number of random bits needed to obtain the Ting and Yao result. We provide a deterministic O (k log n) algorithm for finding the elements which are larger than a given element, given a bound k on the number of these elements. We use this algorithm to obtain an O (log2 n) random bits and O (log2 n) queries algorithm for finding the maximum. Copyright 2001 Academic Press.
Year
DOI
Venue
1996
10.1006/inco.2000.3012
Information and Computation/information and Control
Keywords
DocType
Volume
decisional complexity,yao result,log2 n,randomized decisional complexity,queries algorithm,random bit,k log n,deterministic o,n element,algebraic decision,decision tree,information processing,lower bound
Conference
167
Issue
ISSN
Citations 
1
Information and Computation
0
PageRank 
References 
Authors
0.34
28
2
Name
Order
Citations
PageRank
Moni Naor1129481311.21
Sitvanit Ruah229313.04