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When selecting from, or sorting, a file stored on a read-only tape and the internal storage is rather limited, several passes of the input tape may be required. We study the relation between the amount of internal storage available and the number of passes required to select the Kth highest of N inputs. We show, for example, that to find the median in two(More)
This paper focuses on space efficient representations of rooted trees that permit basic navigation in constant time. While most of the previous work has focused on binary trees, we turn our attention to trees of higher degree. We consider both cardinal trees (or k-ary tries), where each node has k slots, labelled {1,...,k}, each of which may have a(More)
We consider a router on the Internet analyzing the statistical properties of a TCP/IP packet stream. A fundamental difficulty with measuring traffic behavior on the Internet is that there is simply too much data to be recorded for later analysis, on the order of gigabytes a second. As a result, network routers can collect only relatively few statistics(More)
We consider a generalization of the problem of supporting rank and select queries on binary strings. Given a string of length <i>n</i> from an alphabet of size &sigma;, we give the first representation that supports <i>rank</i> and <i>access</i> operations in <i>O</i>(lg lg &sigma;) time, and <i>select</i> in <i>O</i>(1) time while using the optimal(More)
We present a new representation for suffix trees, a data structure used in full text searching, that uses little more storage than the lg n bits per index point required to store the list of index points. We also show algorithms for maintaining the structure on secondary storage in such a way that we minimize the number of disk accesses while searching and(More)
Motivated by boolean queries in text database systems, we consider the problems of finding the intersection, union, or difference of a collection of sorted sets. While the worst-case complexity of these problems is straightforward, we consider a not ion of complexity that depends on the particular instance. We develop the idea of a proof that a given set is(More)
We consider heuristics which attempt to maintain a binary search tree in a near optimal form, assuming that elements are requested with fixed, but unknown, independent probabilities. A "move to root" heuristic is shown to yield an expected search time within a constant factor of that of an optimal static binary search tree. On the other hand, a closely(More)