The database of interval orders difficult for the jump number minimizing algorithms

Przemysław Krysztowiak
2011 Annales UMCS Informatica  
The problems of scheduling jobs on a single machine subject to precedence constraints can often be modelled as the jump number problem for posets, where a linear extension of a given partial order is to be found which minimizes the number of noncomparabilities. In this paper, we are investigating a restricted class of posets, called interval orders, admitting approximation algorithms for the jump number problem, in which the problem remains NP-complete. We have implemented three known
more » ... ion algorithms for this problem, all of which are guaranteed to produce solutions that are at most 50% worse than the optimal ones. More importantly, we have performed an exhaustive search for particularly hard interval orders, which enforce the algorithms to generate orderings which are exactly 50% worse than the optimal linear extensions. The main purpose of this paper is to present the database of those problematic posets. * pk@mat.umk.pl Pobrane z czasopisma Annales AI-Informatica http://ai.annales.umcs.pl
doi:10.2478/v10065-011-0025-4 fatcat:t6e7o7ppincpvd6x5c24to77eq