Let G be some simple graph and k be any positive integer. Take h : V ( G )- {0,1, , ... ,k+1} and v is an element of V (G), let AN(h)(v) denote the set of vertices w is an element of N-G (v) with h (w) >= 1. Let AN...
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Let G be some simple graph and k be any positive integer. Take h : V ( G )- {0,1, , ... ,k+1} and v is an element of V (G), let AN(h)(v) denote the set of vertices w is an element of N-G (v) with h (w) >= 1. Let AN(h)[v] h [v] = AN(h)(v) boolean OR {v}. The function h is a [k]-Roman dominating function of G if h ( AN(h)[v]) >= |AN(h)(v)|+ k holds for any v is an element of V(G). The minimum weight of such a function is called the k-th Roman Domination number of G, which is denoted by gamma(kR) (G). In 2020, Banerjee et al. presented linear timealgorithms to compute the double Roman domination number on proper interval graphs and block graphs. They posed the open question that whether there is some polynomial time algorithm to solve the double Roman domination problem on interval graphs. It is argued that the interval graph is a nontrivial graph class. In this article, we design a simple dynamic polynomial time algorithm to solve the k-th Roman domination problem on interval graphs for each fixed integer k > 1.
The single-item lot sizing problem under a periodic energy limitation is considered in this paper. Identical and parallel capacitated machines constitute the production system, each one consuming a certain amount of e...
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The single-item lot sizing problem under a periodic energy limitation is considered in this paper. Identical and parallel capacitated machines constitute the production system, each one consuming a certain amount of energy when being switched on, when reserved, and when producing. We consider a cost for starting-up the machines, a reservation cost to keep the machines ready for production, in addition to classical lot sizing costs, such as, joint setup cost, unit production cost and unit holding cost, all being time-dependent. Besides the classical lot sizing decisions of how much and in which periods to produce, we have to decide the number of machines to switch on and to switch off in each period. We show that this problem is NP-hard even under restricted conditions. In contrast, assuming stationary energy parameters, we propose two polynomialtime dynamic programming algorithms to solve the problem to optimality. The first algorithm is proposed for the case with null setup cost, null reservation cost and null reservation energy consumption, and runs in O ((MT4)-T-5) time, with M being the number of machines and T the number of periods. We show that we can extend this algorithm to solve the generalized version of the problem in time complexity O ((MT6)-T-6).
Graph burning is a model for the spread of social contagion. The burning number is a graph parameter associated with graph burning that measures the speed of the spread of contagion in a graph;the lower the burning nu...
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Graph burning is a model for the spread of social contagion. The burning number is a graph parameter associated with graph burning that measures the speed of the spread of contagion in a graph;the lower the burning number, the faster the contagion spreads. We prove that the corresponding graph decision problem is NP-complete when restricted to acyclic graphs with maximum degree three, spider graphs and path-forests. We provide polynomial time algorithms for finding the burning number of spider graphs and path forests if the number of arms and components, respectively, are fixed. Finally, we describe a polynomialtime approximation algorithm with approximation factor 3 for general graphs. (C) 2017 Elsevier B.V. All rights reserved.
We identify a polynomially solvable special case of the bounded knapsack problem that is characterized by a set of simple inequalities relating item weight ratios to item profit ratios. Our result generalizes and exte...
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We identify a polynomially solvable special case of the bounded knapsack problem that is characterized by a set of simple inequalities relating item weight ratios to item profit ratios. Our result generalizes and extends a corresponding result of Zukerman, et al. [M. Zukerman, L. Jia, T. Neame, G.J. Woeginger, A polynomially solvable special case of the unbounded knapsack problem, Operations Research Letters 29 (2001) 13-16] for the unbounded knapsack problem. (c) 2011 Elsevier B.V. All rights reserved.
This paper considers some scheduling problems with deteriorating jobs and learning effects. The following objective functions are considered: the makespan, the total completion times, and the total absolute difference...
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This paper considers some scheduling problems with deteriorating jobs and learning effects. The following objective functions are considered: the makespan, the total completion times, and the total absolute differences in completion times. Several polynomial time algorithms are proposed to optimally solve the single-machine scheduling problems. Finally, we show that several special cases of the flowshop scheduling problems remain polynomially solvable under the proposed model. (C) 2009 Published by Elsevier Ltd.
This study considers a typical scheduling environment that is influenced by the behavioral phenomenon of multitasking. Under multitasking, the processing of a selected job suffers from interruption by other jobs that ...
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This study considers a typical scheduling environment that is influenced by the behavioral phenomenon of multitasking. Under multitasking, the processing of a selected job suffers from interruption by other jobs that are available but unfinished. This situation arises in a wide variety of applications;for example, administration, manufacturing, and process and project management. Several classical solution methods for scheduling problems no longer apply in the presence of multitasking. The solvability of any scheduling problem under multitasking is no easier than that of the corresponding classical problem. We develop optimal algorithms for some fundamental and practical single machine scheduling problems with multitasking. For other problems, we show that they are computationally intractable, even though in some cases the corresponding problem in classical scheduling is efficiently solvable. We also study the cost increase and value gained due to multitasking. This analysis informs companies about how much it would be worthwhile to invest in measures to reduce or encourage multitasking.
In this paper, we consider the class of Boolean mu-functions, which are the Boolean functions definable by mu-expressions (Boolean expressions in which no variable occurs more than once). We present an algorithm which...
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In this paper, we consider the class of Boolean mu-functions, which are the Boolean functions definable by mu-expressions (Boolean expressions in which no variable occurs more than once). We present an algorithm which transforms a Boolean formula E into an equivalent mu-expression-if possible-in time linear in parallel to E parallel to times 2(nm), where parallel to E parallel to is the size of E and n(m) is the number of variables that occur more than once in E. As an application, we obtain a polynomial time algorithm for Mundici's problem of recognizing mu-functions from k-formulas [17]. Furthermore, we show that recognizing Boolean mu-functions is co-NP-complete for functions essentially dependent on all variables and we give a bound close to co-NP for the general case.
We describe a method that will reconstruct an unrooted binary phylogenetic level-1 network on taxa from the set of all quartets containing a certain fixed taxon, in time. We also present a more general method which ca...
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We describe a method that will reconstruct an unrooted binary phylogenetic level-1 network on taxa from the set of all quartets containing a certain fixed taxon, in time. We also present a more general method which can handle more diverse quartet data, but which takes time. Both methods proceed by solving a certain system of linear equations over the two-element field . For a general dense quartet set, i.e. a set containing at least one quartet on every four taxa, our algorithm constructs a phylogenetic level-1 network consistent with the quartet set if such a network exists and returns an -sized certificate of inconsistency otherwise. This answers a question raised by Gambette, Berry and Paul regarding the complexity of reconstructing a level-1 network from a dense quartet set, and more particularly regarding the complexity of constructing a cyclic ordering of taxa consistent with a dense quartet set.
In many combinatorial situations there is a notion of independence of a set of points. Maximal independent sets can be easily constructed by a greedy algorithm, and it is of interest to determine, for example, if they...
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In many combinatorial situations there is a notion of independence of a set of points. Maximal independent sets can be easily constructed by a greedy algorithm, and it is of interest to determine, for example, if they all have the same size or the same parity. Both of these questions may be formulated by weighting the points with elements of an abelian group, and asking whether all maximal independent sets have equal weight. If a set is independent precisely when its elements are pairwise independent, a graph can be used as a model. The question then becomes whether a graph, with its vertices weighted by elements of an abelian group, is well-covered, i.e., has all maximal independent sets of vertices with equal weight. This problem is known to be co-NP-complete in general. We show that whether a graph is well-covered or not depends on its local structure. Based on this, we develop an algorithm to recognize well-covered graphs. For graphs with n vertices and maximum degree Delta, it runs in linear time if Delta is bounded by a constant, and in polynomialtime if Delta = O((3)root log n). We mention various applications to areas including hypergraph matchings and radius k independent sets. We extend our results to the problem of determining whether a graph has a weighting which makes it well-covered.
We provide polynomial time algorithms for deciding equation solvability and identity checking over groups that are semidirect products of two finite Abelian groups. Our main method is to reduce these problems to the s...
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We provide polynomial time algorithms for deciding equation solvability and identity checking over groups that are semidirect products of two finite Abelian groups. Our main method is to reduce these problems to the sigma equation solvability and sigma equivalence problems over modules for commutative unital rings. (C) 2015 Elsevier Inc. All rights reserved.
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