Pure greedy algorithm(PGA), orthogonal greedy algorithm(OGA) and relaxed greedy algorithm(RGA) are three widely used greedy type algorithms in both nonlinear approximation and supervised *** this paper, we apply anoth...
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Pure greedy algorithm(PGA), orthogonal greedy algorithm(OGA) and relaxed greedy algorithm(RGA) are three widely used greedy type algorithms in both nonlinear approximation and supervised *** this paper, we apply another variant of greedy-type algorithm, called the truncated greedy algorithm(TGA)in the realm of supervised learning and study its learning performance. We rigorously prove that TGA is better than PGA in the sense that TGA possesses the faster learning rate than PGA. Furthermore, in some special cases, we also prove that TGA outperforms OGA and RGA. All these theoretical assertions are verified by both toy simulations and real data experiments.
This paper examines specific classes of conventional decision tables (DTs) that are closed under operations of attribute (column) removal and decision modifications assigned to rows. For DTs belonging to any of these ...
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ISBN:
(纸本)9783031656644;9783031656651
This paper examines specific classes of conventional decision tables (DTs) that are closed under operations of attribute (column) removal and decision modifications assigned to rows. For DTs belonging to any of these closed classes (CCs), we investigate a greedy algorithm that constructs a deterministic decision tree. We demonstrate that the number of steps performed by this algorithm is limited by twice the number of rows in the table. Furthermore, we compare the behavior of two functions. The first function describes the increase in the minimum complexity of a deterministic decision tree for a DT from the CC in the worst-case scenario, in relation to the complexity of the set of attributes associated with columns of the table. The second function characterizes the worst-case complexity growth of the deterministic decision tree constructed by the greedy algorithm for a DT from the CC, considering the growth of complexity of the set of attributes associated with columns of the table. We divide the entire collection of pairs consisting of a bounded complexity measure (BCM) and a CC into three subsets. For each subset, we establish lower and upper bounds for the second function based on the first function.
An strategic restoration scheme of the power system is able to reduce the load losses during blackouts. The generator start-up sequence is the key of the restoration strategy that determines the time consumed in power...
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ISBN:
(纸本)9781538682180
An strategic restoration scheme of the power system is able to reduce the load losses during blackouts. The generator start-up sequence is the key of the restoration strategy that determines the time consumed in power system restoration. This paper proposes an optimization method to determine the generator start-up sequence with consideration of transmission path. First, the recovery models of generator and transmission path are developed to explicitly model their recovery time under different conditions. Then, the equivalent generator resilience index is defined to determine the generator start-up priority. Finally, a greedy algorithm based method is proposed to optimizing generator start-up sequence to maximize the equivalent generator resilience index at each step of the restoration process while considering the transmission paths. The simulation results obtained by the IEEE 39-bus test system demonstrate the effectiveness of the proposed method.
Deformable models, such as the discrete active contour and surface, imply the use of iterative evolution methods to perform 2D and 3D image segmentation. Among the several existing evolution methods, we focus on the g...
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ISBN:
(纸本)9781424404810
Deformable models, such as the discrete active contour and surface, imply the use of iterative evolution methods to perform 2D and 3D image segmentation. Among the several existing evolution methods, we focus on the greedy algorithm, which minimizes an energy functional, and the physics-based method, which applies forces in order to solve a dynamic differential equation. In this paper, we compare the greedy and physics-based approaches applied on 2D and 3D models, as regards overall speed and segmentation quality, quantified with an evaluating function mainly based on the mean distance between the model and the desired shape.
Deformable models have been quite popular in medical image analysis, particularly in image segmentation. However, when applied to 3D volumetric data, their high computational cost can be a problem. In this paper, we d...
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ISBN:
(纸本)9781479958382
Deformable models have been quite popular in medical image analysis, particularly in image segmentation. However, when applied to 3D volumetric data, their high computational cost can be a problem. In this paper, we describe a new efficient 3D segmentation method based on deformable simplex meshes. The greedy algorithm, which has proven more computational efficient and robust than physics-based method, is employed to perform the shape deformation. Generalized gradient vector flow (GGVF) field is a classical external force for physics-based deformable models. We adapt it for greedy algorithm as external energy to overcome the main issues of the traditional external energy (i.e., sensitivity to shape initialization and poor convergence to the long and thin boundary concavities). Results of applying our method to both synthetic and clinical images are presented to illustrate the accuracy and robustness of our proposed method.
Inventory routing problem (IRP) is one of the emerging solutions for improving the supply chain efficiency. It gives the vendors the responsibility to monitor and decide the inventory replenishments of their customers...
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Inventory routing problem (IRP) is one of the emerging solutions for improving the supply chain efficiency. It gives the vendors the responsibility to monitor and decide the inventory replenishments of their customers. The Inventory Routing Problem (IRP) is an evolved component of VMI policies. Inventory routing provides a win-win situation for both vendors and customers. In this paper we consider a one or more distribution network consisting of a single depot and many geographically dispersed customers where each customer faces demands for a single item which, arise at a deterministic and customer-specific rate. The problem addressed in this paper is based on a finite horizon, multi-period and single product where a fleet of capacitated vehicles transport items from the depot to meet the demand specified by the customers for each period. Here a greedy algorithm is used for finding an optimal route and routing cost associated with it, finding an inventory and transportation cost that minimizes the total cost. (C) 2019 Elsevier Ltd. All rights reserved.
For a graph G = (V, E), a vertex set C subset of V is an m-f old outer-connected dominating set (m-f old OCDS) of G if every vertex in V\C has at least m neighbors in C and the subgraph of G induced by V\C is connecte...
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For a graph G = (V, E), a vertex set C subset of V is an m-f old outer-connected dominating set (m-f old OCDS) of G if every vertex in V\C has at least m neighbors in C and the subgraph of G induced by V\C is connected. In this paper, we present a greedy algorithm to compute an m-fold OCDS in general graphs, which returns a solution of size at most alpha + 1+ln(Delta + m + 1) times that of aminimum m-fold OCDS, where Delta is the maximum degree of the graph and alpha is a positive number at most Delta+m+1.
In the paper, an optimization of alpha-Association rules constructed by greedy algorithm is proposed. It allows us to decrease the number of rules and obtain short rules, what is important from the point of view of kn...
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ISBN:
(纸本)9783319396309;9783319396293
In the paper, an optimization of alpha-Association rules constructed by greedy algorithm is proposed. It allows us to decrease the number of rules and obtain short rules, what is important from the point of view of knowledge representation. Experimental results for data sets from UCI Machine Learning Respository are presented.
Let 0 = 1;(c) there exists t >= 1 such that b(n)/a(n) = 2 and a(n) -> infinity, there exist theta and (b(n)) such that (a) and (b) are satisfied;whether (c) is also satisfied depends on the sequence (a(n)). Fina...
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Let 0 < theta <= 1. A sequence of positive integers (b(n))(n=1)(infinity) is called a weak greedy approximation of theta if Sigma(infinity)(n=1) 1/b(n) = theta. We introduce the weak greedy approximation algorithm (WGAA), which, for each theta, produces two sequences of positive integers (a(n)) and (b(n)) such that (a) Sigma(infinity)(n=1) 1/b(n) = theta;(b) 1/a(n+1) < theta - Sigma(n)(i=1) 1/b(i) < 1/(a(n+1) - 1) for all n >= 1;(c) there exists t >= 1 such that b(n)/a(n) <= t infinitely often. We then investigate when a given weak greedy approximation (b(n)) can be produced by the WGAA. Furthermore, we show that for any non-decreasing (a(n)) with a(1) >= 2 and a(n) -> infinity, there exist theta and (b(n)) such that (a) and (b) are satisfied;whether (c) is also satisfied depends on the sequence (a(n)). Finally, we address the uniqueness of theta and (b(n)) and apply our framework to specific sequences. (c) 2023 Royal Dutch Mathematical Society (KWG). Published by Elsevier B.V. All rights reserved.
While most improved snakes were built under the original variational scheme, this paper presents an attractable snake based on the greedy snake (Williams and Shah, CVGIP: Image Understanding 55(1) (1992) 14-26). By us...
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While most improved snakes were built under the original variational scheme, this paper presents an attractable snake based on the greedy snake (Williams and Shah, CVGIP: Image Understanding 55(1) (1992) 14-26). By use of a direct feedback mechanism that is seamlessly consistent with the search strategy of the greedy algorithm, the proposed approach is capable of inheriting the simplicity and efficiency of that algorithm and performing competitively with related snakes. To avoid undesirable local minima, an overall optimal edge detector is designed. A suitable synthetic convergent criterion is proposed which enables snakes to converge normally or oscillatingly on target objects. An adaptive interpolation scheme that encourages snakes to accurately sense the details of object shapes is also described. This model is applied to extract contours from various images with encouraging results. (C) 2002 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.
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