منابع مشابه
ON RELATIVE CENTRAL EXTENSIONS AND COVERING PAIRS
Let (G;N) be a pair of groups. In this article, first we con-struct a relative central extension for the pair (G;N) such that specialtypes of covering pair of (G;N) are homomorphic image of it. Second, weshow that every perfect pair admits at least one covering pair. Finally,among extending some properties of perfect groups to perfect pairs, wecharacterize covering pairs of a perfect pair (G;N)...
متن کاملEffective heuristics for the Set Covering with Pairs Problem
This paper deals with the Set Covering with Pairs Problem (SCPP). This problem is a generalization of the Set Covering Problem (SCP), which is known to be NP-hard. The difference between both problems is that, in the SCPP, one element of the universe is admitted to be covered if there are at least two specific objects chosen to cover it. In this context, three constructive heuristics, one local...
متن کاملA cross entropy algorithm for continuous covering location problem
Covering problem tries to locate the least number of facilities and each demand has at least one facility located within a specific distance.This paper considers a cross entropy algorithm for solving the mixed integer nonlinear programming (MINLP) for covering location model.The model is solved to determine the best covering value.Also, this paper proposes aCross Entropy (CE) algorithm consider...
متن کاملCovering and packing for pairs
a Division of Mathematical Sciences, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore b Computing, Informatics, and Decision Systems Engineering, Arizona State University, Tempe, AZ 85287-8809, USA c Department of Computer Science, University of Vermont, Burlington, VT 05405, USA d Department of Mathematics, 253-37, Cal...
متن کاملDynamic Hub Covering Problem with Flexible Covering Radius
Abstract One of the basic assumptions in hub covering problems is considering the covering radius as an exogenous parameter which cannot be controlled by the decision maker. Practically and in many real world cases with a negligible increase in costs, to increase the covering radii, it is possible to save the costs of establishing additional hub nodes. Change in problem parameters during the pl...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 1982
ISSN: 0012-365X
DOI: 10.1016/0012-365x(82)90082-6