A Better-Than-Greedy Algorithm for k-Set Multicover

2006 ◽  
pp. 176-189 ◽  
Author(s):  
Toshihiro Fujito ◽  
Hidekazu Kurahashi
Keyword(s):  
Greedy Algorithm ◽  
Better Than

scholarly journals Greedy, A-Star, and Dijkstra’s Algorithms in Finding Shortest Path

2021 ◽  
Vol 2 (1) ◽  
pp. 45-52
Author(s):  
Muhammad Rhifky Wayahdi ◽  
Subhan Hafiz Nanda Ginting ◽  
Dinur Syahputra
Keyword(s):  
Greedy Algorithm ◽  
Shortest Path ◽  
Optimal Solution ◽  
The Other ◽  
Complex Data ◽  
Dijkstra’S Algorithm ◽  
Dijkstra's Algorithm ◽  
The Greedy Algorithm ◽  
Better Than

The problem of finding the shortest path from a path or graph has been quite widely discussed. There are also many algorithms that are the solution to this problem. The purpose of this study is to analyze the Greedy, A-Star, and Dijkstra algorithms in the process of finding the shortest path. The author wants to compare the effectiveness of the three algorithms in the process of finding the shortest path in a path or graph. From the results of the research conducted, the author can conclude that the Greedy, A-Star, and Dijkstra algorithms can be a solution in determining the shortest path in a path or graph with different results. The Greedy algorithm is fast in finding solutions but tends not to find the optimal solution. While the A-Star algorithm tends to be better than the Greedy algorithm, but the path or graph must have complex data. Meanwhile, Dijkstra's algorithm in this case is better than the other two algorithms because it always gets optimal results.

A Genetic Algorithm for Flow Scheduling in Data Center Networks

2015 ◽  
Vol 713-715 ◽  
pp. 2414-2417
Author(s):  
Bo Yang ◽  
Wei Peng ◽  
Xing Zhou
Keyword(s):  
Genetic Algorithm ◽  
Greedy Algorithm ◽  
Data Center ◽  
Data Center Networks ◽  
Link Utilization ◽  
Single Link ◽  
Better Than

Traffic in today’s data center networks grows rapidly. Traditional routing and forwarding protocols in data center usually rely on static hashing, and may cause avoidable bottlenecks. We present a genetic algorithm to make better use of the resources. Our goal is to minimize the maximum single link utilization of the network. And results show that our algorithm performs better than a recent greedy algorithm.

scholarly journals Order Fulfillment Decision under Multiwarehouse Collaborative Delivery

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Song Shuanjun ◽  
Peng Longguang ◽  
Meng Yuanyi ◽  
Hu Sheng
Keyword(s):  
Linear Programming ◽  
Greedy Algorithm ◽  
Programming Algorithm ◽  
Second Step ◽  
Strategy Selection ◽  
Order Fulfillment ◽  
Linear Programming Algorithm ◽  
The Cost ◽  
Delivery Location ◽  
Better Than

Aiming at the high cost of multicategory orders fulfillment under multiwarehouse collaborative distribution, comprehensively considering the fulfillment costs of different orders fulfillment strategies, an order fulfillment strategy selection model is proposed. The first step of the model uses the linear programming algorithm to solve the cost of suborder merge transportation after the order is split. The second step calculates the cost of the current “greedy algorithm” of the e-commerce platform for order split fulfillment. Then, the cost of each strategy is compared and the lowest cost one is chosen. The calculation example analysis shows that the order fulfillment strategy is closely related to the delivery location of the order and the SKU category. When the delivery location is far away and SKU categories are many in the order, the merged transportation strategy of suborders after the order is split will be significantly better than the cost of separate transportation. The multiwarehouse collaborative distribution fulfillment strategy proposed in this paper can provide a decision basis for the e-commerce platform to choose which fulfillment method.

ON THE k-TRUCK SCHEDULING PROBLEM

2004 ◽  
Vol 15 (01) ◽  
pp. 127-141 ◽  
Author(s):  
WEIMIN MA ◽  
YINFENG XU ◽  
JANE YOU ◽  
JAMES LIU ◽  
KANLIANG WANG
Keyword(s):  
Lower Bound ◽  
Greedy Algorithm ◽  
Competitive Ratio ◽  
Scheduling Problem ◽  
Competitive Algorithm ◽  
Truck Scheduling ◽  
New Variant ◽  
On Line ◽  
Server Problem ◽  
Better Than

In this paper, some results concerning the k-truck problem are produced. Firstly, the algorithms and their complexity concerning the off-line k-truck problem are discussed. Following that, a lower bound of competitive ratio (1+θ)·k/(θ·k+2) for the on-line k-truck problem is given, where θ is the ratio of cost of the loaded truck and the empty truck on the same distance, and a relevant lower bound for the on-line k-taxi problem followed naturally. Thirdly, based on the Position Maintaining Strategy (PMS), some new results which are slightly better than those of [11] for general cases are obtained. For example, a c-competitive or (c/θ+1/θ+1)-competitive algorithm for the on-line k-truck problem depending on the value of θ, where c is the competitive ratio of some algorithm to a relevant k-server problem, is developed. The Partial-Greedy Algorithm (PG) is used as well to solve this problem on a line with n nodes and is proved to be a (1+(n-k)/θ)-competitive algorithm for this case. Finally, the concepts of the on-line k-truck problem are extended to obtain a new variant: Deeper On-line k-Truck Problem (DTP). We claim that results of PMS for the STP (Standard Truck Problem) hold for the DTP.

On the Power of Lookahead in Greedy Scheme for Finding a Minimum CDS for Unit Disk Graphs

2016 ◽  
Vol 27 (07) ◽  
pp. 829-843
Author(s):  
Satoshi Fujita
Keyword(s):  
Unit Disk ◽  
Greedy Algorithm ◽  
Dominating Set ◽  
Performance Ratio ◽  
Connected Subgraph ◽  
Bounded Degree ◽  
Unit Disk Graphs ◽  
Optimum Solution ◽  
General Graphs ◽  
Better Than

A connected dominating set (CDS, for short) for graph G is a dominating set which induces a connected subgraph of G. In this paper, we consider the problem of finding a minimum CDS for unit disk graphs, which have recently attracted considerable attention as a model of virtual backbone in multi-hop wireless networks. This optimization problem is known to be NP-hard and many approximation algorithms have been proposed in the literature. This paper proves a lower bound on the performance ratio of a greedy algorithm of Guha and Khuller which was originally proposed for general graphs and is known to be a representative in which the lookahead plays a crucial role in selecting a vertex to be contained in the CDS. More specifically, we show that for any fixed ε>0 and integer n0≥1, there is a unit disk graph with bounded degree consisting of at least n0 vertices for which the output of the greedy algorithm is no better than 3−ε times of an optimum solution to the same graph.

A Novel Reliability-Driven Heuristic for Grid Task Scheduling

2013 ◽  
Vol 291-294 ◽  
pp. 2895-2898
Author(s):  
Lin Wu ◽  
Cai Li Fang ◽  
Cao Kun Yan
Keyword(s):  
Greedy Algorithm ◽  
Task Scheduling ◽  
Scheduling Algorithms ◽  
Experimental Results ◽  
Task Completion ◽  
Failure Condition ◽  
Grid Environment ◽  
Heuristic Strategy ◽  
Better Than

Under dynamic, unreliable grid environment, a novel heuristic based on average reliability of task is proposed, which task into account the failure condition and dynamic workload of Grid. On the basis of the heuristic strategy proposed, this paper improved two classic scheduling algorithms, Min-min and Sufferage, to improve execution reliability of grid task. Moreover, a new greedy algorithm, GR, is proposed in the paper. The simulation experimental results indicate that the algorithms based on the average reliability heuristic are better than Min-min and Sufferage in terms of task completion ratio by 10%, which can guarantee the user's deadline efficiently.

scholarly journals A Greedy Algorithm for Over-The-Cell Channel Routing

VLSI Design ◽  
1996 ◽  
Vol 5 (1) ◽  
pp. 23-36
Author(s):  
Gudni Gudmundsson ◽  
Simeon Ntafos
Keyword(s):  
Greedy Algorithm ◽  
Final Stage ◽  
Maximum Density ◽  
Greedy Heuristics ◽  
Channel Routing ◽  
Channel Density ◽  
Recent Advances ◽  
Vlsi Technology ◽  
Better Than

Recent advances in VLSI technology have made the area over cells available for routing. In this paper we present a new over-the-cell channel router that uses greedy heuristics to make the over-the-cell connections and to define the nets needed to complete the connections inside the channel. The router tries to reduce the channel density by moving segments that cross maximum density columns to the over-the-cell areas. The layout model used allows only planar connections over each cell. The final stage is to use an existing channel router to route the connections inside the channel. An important characteristic of the new router is that there is interaction between the decisions made for the over-the-cell connections and the connections needed inside the channel. It performs significantly better than previous over the-cell routers.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Localization of immunolabels by electron microscopy and image averaging

1983 ◽  
Vol 41 ◽  
pp. 282-283
Author(s):  
J. Frank ◽  
P.-Y. Sizaret ◽  
A. Verschoor ◽  
J. Lamy
Keyword(s):  
Electron Microscopy ◽  
Single Particle ◽  
Attachment Site ◽  
Uranyl Acetate ◽  
Limulus Polyphemus ◽  
Resolution Limit ◽  
Electron Microscopic ◽  
Image Averaging ◽  
Top View ◽  
Better Than

The accuracy with which the attachment site of immunolabels bound to macromolecules may be localized in electron microscopic images can be considerably improved by using single particle averaging. The example studied in this work showed that the accuracy may be better than the resolution limit imposed by negative staining (∽2nm).The structure used for this demonstration was a halfmolecule of Limulus polyphemus (LP) hemocyanin, consisting of 24 subunits grouped into four hexamers. The top view of this structure was previously studied by image averaging and correspondence analysis. It was found to vary according to the flip or flop position of the molecule, and to the stain imbalance between diagonally opposed hexamers (“rocking effect”). These findings have recently been incorporated into a model of the full 8 × 6 molecule.LP hemocyanin contains eight different polypeptides, and antibodies specific for one, LP II, were used. Uranyl acetate was used as stain. A total of 58 molecule images (29 unlabelled, 29 labelled with antl-LPII Fab) showing the top view were digitized in the microdensitometer with a sampling distance of 50μ corresponding to 6.25nm.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

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