On Approximations and Reductions

Polynomial-Time Reductions, NP-Completeness, and Approximations 1

on semihypergroups and hypergroups

in this thesis, first the notion of weak mutual associativity (w.m.a.) and the necessary and sufficient condition for a $(l,gamma)$-associated hypersemigroup $(h, ast)$ derived from some family of $lesssim$-preordered semigroups to be a hypergroup, are given. second, by proving the fact that the concrete categories, semihypergroups and hypergroups have not free objects we will introduce t...

Matrix-based set approximations and reductions in covering decision information systems

Article history: Received 21 June 2014 Received in revised form 12 October 2014 Accepted 12 January 2015 Available online 7 February 2015

compactifications and function spaces on weighted semigruops

chapter one is devoted to a moderate discussion on preliminaries, according to our requirements. chapter two which is based on our work in (24) is devoted introducting weighted semigroups (s, w), and studying some famous function spaces on them, especially the relations between go (s, w) and other function speces are invesigated. in fact this chapter is a complement to (32). one of the main fea...

On Reductions for the

Several authors have demonstrated the use of reductions in order to decrease the diiculty of solving the Steiner Problem in Graphs. This paper develops the theory of connuence as it relates to graph reduction , and uses this theory to gain insights into how the maximum amount of reduction can be obtained.