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| A Data Reduction Algorithm with Unification of Attribute and Attribute Value |
| DENG Shao-Bo1, GUAN Su-Jie1 , Li Min1, LIU Qing1,2 |
1.Department of Computer Science and Technology, Nanchang Institute of Technology, Nanchang 330099
2.Department of Computer Science, Nanchang University, Nanchang 330029 |
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Abstract A data reduction algorithm is proposed. It takes account of the equivalence class family of condition attributes in the decision table. Through analyzing the equivalence class family of decision value, both the attribute reduction and the attribute value reduction can be performed simultaneously in the process of reduction in a decision table. Compared with the traditional method based on the analytical method or discernibility matrix method, the proposed algorithms can omit the complicated comparison process in the reduction of the attribute value. The comparison times can be decreased and the reduction efficiency can be improved by the proposed algorithm.
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Received: 01 June 2007
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[1]～[4].
2 属性与属性值合一约简算法
合一约简算法融合了一般约简方法过程中属性约简与属性值约简这两个步骤,本文约简算法是从决策表的每一列来分析讨论的.而区分矩阵方法与其他基于区分矩阵拓展的约简方法都是从决策表每一行来分析判断的[1,3-4,7-8,15],在属性约简结束后还必需对决策表进行属性值约简.基于区分矩阵约简方法,在文献[17]、[18]中,作者进行详细深入地分析与探讨.对相容决策表与非相容决策表,约简时分别利用代数、信息熵方法进行分析与总结,并提出相应算法.而本文并没有采用区分矩阵方法,本文提出的约简方法属性约简与属性值约简是同时进行的.
已知决策表T=(U,A,C,D),等价类族U/D=｛ E1,…,En ｝中,个体x≠y,x,y∈Ei ,Ei∈U/D,i,j=1,2,…,n,等价类Ej∩Ei=,i≠j.
本文算法主要步骤如下.
输入 决策表T=(U,A,C,D),等价类族U/D=｛E1,…,En｝中,Ei∈U/D,i=1,2,…,n
输出 决策表T的核值表
step 1 求出a∈C, U/a等价类族; U/C=
∩U/a,及U/D等价类族. |
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2009, Vol. 22 
