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What and Who

On-the-fly array initialization

Prof. Torben Hagerup
Universität Augsburg
AG1 Mittagsseminar (own work)
AG 1, AG 2, AG 3, AG 4, AG 5, SWS, RG1, MMCI  
AG Audience
English

Date, Time and Location

Tuesday, 20 December 2016
13:00
30 Minutes
E1 4
24
Saarbrücken

Abstract

We show that for all given positive integers n, t and w with n < 2^w,
an array of n entries of w bits each can be represented on a word RAM
with a word length of w bits in at most n w+ceiling(n (t/(2 w))^t) bits
of uninitialized memory to support constant-time initialization of the
whole array and O(t)-time reading and writing of individual array entries.
At one end of this tradeoff, we achieve initialization and access
(i.e., reading and writing) in constant time with n w+ceiling(n/(w^t)) bits
for arbitrary fixed t, to be compared with n w+Theta(n) bits for the
best previous solution, and at the opposite end, still with constant-time
initialization, we support O(log n)-time access with just n w+1 bits,
which is optimal for arbitrary access times if the initialization
executes fewer than n steps.

Contact

Christina Fries
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Christina Fries, 12/15/2016 14:17
Christina Fries, 12/15/2016 09:46 -- Created document.