Dynamic Three-way Decision Model Based On Updating Of Attribute Values And Its Application

As a classical mathematical tool for data mining and knowledge discover,rough set theory has become an important theory to deal with uncertain or imprecise data in recent years.The three-way decisions is a kind of "three trisection and treatment" model which is gradually evolved from the decision-theoretic rough sets.The core content of the three-way decisions is that a domain is divided into three disjoint regions and the corresponding decision-making strategies for each region are obtained.As an important extension of the traditional two-way decisions,the three-way decision model takes the uncertain factors existing in the decision-making process into account.The deferred decision as the third decision-making behavior when the information is not enough to determine whether an object is absolutely accepted or rejected.The three-way decision model is a topic of substantial research interest in the field of artificial intelligence,and many researchers have focused on to its feasibility and rationality.The tolerance and practicability of the three-way decision model are better than those of the two-way decision model.When the attribute value of each object in a domain is given,the formation of a three-way classification of the domain is a key issue.However,few studies have been conducted on establishing a three-way decision model with the given attribute values in the case where the number of objects in an accepted region is given.According to the above problems,the following contents are researched:(1)On the basis of the existing three-way decision models and their theories,both the uncertainty of attribute values and the cost of updating are fully considered,a dynamic three-way decision model based on updating of numerical attribute values is proposed.Based on analysis of characteristics of numerical attributes and character attributes,first,a feature extraction algorithm of numerical attribute value is proposed.Then,a new concept of attribute ratio is defined to describe an object when the attribute value of the object is numerical,and a corresponding dynamic three-way decision model is established.Meanwhile,when number of accepted object is given,a selection method of the decision thresholds is proposed,and it is demonstrated that the decision thresholds are adaptive in the process of dynamic updating.Next,an example is provided to demonstrate how twoway classification results can be obtained in the dynamic decision-making process.Finally,the results of simulation experiments show that the proposed model is feasible and effective in practical applications.When the number of objects in an accepted region has been given,according to the updating strategy of attribute values,the three-way decision problems are successfully solved by the proposed model.(2)According to the uncertainty of knowledge connotation on the character attributes in the dynamic updating process,based on the same decision-making background,the difference in the degree of excellence between the objects of character attributes are fully considered,and a dynamic three-way decision model based on updating of character attribute values is proposed.The both concept of the fuzzy rank and the fuzzy value of comprehensive evaluation of objects are defined to describe the objects,and the real rank of object can be obtained by a new concept on revised deviation.It is easy to describe the differences between those objects by numeric content.Then,in order to further ensure the difference in the degree of excellence between the objects in the decision-making process,based on Euclidean distance,the true rank is used to calculate the optimal close degree as the real value of comprehensive evaluation of objects.According to the decision-making idea of numerical attributes,the dynamic feature of objects of character attributes is defined in the process of updating and a corresponding dynamic way-decision model is established.Finally,the effectiveness and applicability of the proposed model are proved by a large number of simulation experiments.The proposed model further improves the dynamic decision-making model based on updating of attribute values,and it makes the three-way decisions more widely applied to the actual situation.