MPI-INF Logo
Campus Event Calendar

Event Entry

What and Who

Optimal Sorting with Persistent Comparison Errors

Stefano Leucci
Max-Planck-Institut für Informatik - D1
AG1 Mittagsseminar (own work)
AG 1, MMCI  
AG Audience
English

Date, Time and Location

Tuesday, 22 January 2019
13:00
30 Minutes
E1 4
024
Saarbrücken

Abstract

We consider the problem of sorting n elements in the case of persistent comparison errors. In this problem, each comparison between two elements can be wrong with some fixed (small) probability p, and comparisons cannot be repeated (Braverman and Mossel, SODA'08).

Sorting perfectly in this model is impossible, and the objective is to minimize the dislocation of each element in the output sequence, that is, the difference between its true rank and its position. Existing lower bounds for this problem show that no algorithm can guarantee, with high probability, maximum dislocation and total dislocation better than Omega(log n) and Omega(n), respectively, regardless of its running time.
We present the first O(n log n)-time sorting algorithm that guarantees both O(log n) maximum dislocation and O(n) total dislocation with high probability.
This settles the time complexity of this problem and shows that comparison errors do not make the problem computationally more difficult: a sequence with the best possible dislocation can be obtained in O(n log n) time and, even without comparison errors, Omega(n log n) time is necessary to guarantee such dislocation bounds.

Contact

Nitin Saurabh
--email hidden
passcode not visible
logged in users only

Nitin Saurabh, 01/14/2019 08:43 -- Created document.