TRANS outperforms MTF for two special types of request sequences without locality of reference

TL;DR

This paper analytically compares TRANS and MTF list accessing algorithms, demonstrating that TRANS outperforms MTF for specific request sequences lacking locality of reference, highlighting circumstances favoring TRANS.

Contribution

The paper provides the first analytical performance comparison of TRANS and MTF algorithms on special request sequences without locality of reference.

Findings

TRANS outperforms MTF for the considered request sequences

Analytical bounds are established for TRANS and MTF performance

Highlights conditions where TRANS is preferable over MTF

Abstract

Various list accessing algorithms have been proposed in the literature and their performances have been analyzed theoretically and experimentally. Move-To-Front (MTF) and Transpose (TRANS) are two well known primitive list accessing algorithms. MTF has been proved to be the best performing online algorithm till date in the literature for real life inputs and practical applications with locality of reference. It has been shown that when storage space is extremely limited and pointers for lists cannot be used, then array implementation of TRANS gives efficient reorganization. Use of MTF is extensive in the literature whereas, the use of TRANS is rare. As mentioned as an open problem in literature, direct bounds on the behavior and performance of various list accessing algorithms are needed to allow realistic comparisons. Since it has been shown that no single optimal permutation algorithm exists, it becomes necessary to characterize the circumstances that indicate the advantage in using a particular list accessing algorithm. Motivated by above challenging research issue, in this paper we have made an analytical study for evaluating the performance of TRANS list accessing algorithm using two special types of request sequences without locality of reference. We have compared the performance of TRANS with MTF and observed that TRANS outperforms MTF for these considered types of request sequences.