Concerning the problem of privacy leak of personal location when querying the nearest neighbor location in social network, a geo-indistinguishability mechanism was used to add random noise to the location data, and a privacy budget allocation method was proposed. First, the spatial regions were divided into grids, and the personalized privacy budget allocation was performed according to the location hits of user in different regions. Then, in order to solve the problem of low hit rate of the neighbor query in the disturbance location dataset, a Combined Incremental Neighbor Query (CINQ) algorithm was proposed to expand the search range of the demand space, and the combination query was used to filter out the redundancy data. Simulation results show that compared with the SpaceTwist algorithm, the CINQ algorithm had the query hit rate increased by 13.7 percentage points. Experimental results verify that the CINQ algorithm effectively solves the problem of low query hit rate caused by the location disturbance of the query target, and it is suitable for neighbor queries for disturbed locations in social network applications.

Aiming at the problem of decision error caused by similarity collision in evidence theory, a new combination rule for evidence theory was proposed. Firstly, the features of focal-element sequence in evidence were extracted and converted into a sort matrix to reduce similarity collision. Secondly, the weight of each evidence was determined based on sort matrix and information entropy. Finally, the Modified Average Evidence (MAE) was generated based on the evidence set and evidence weight, and the combination result was obtained by combing MAE for n-1 times by using Dempster combination rule. The experimental results on the online dataset Iris show that the F-Score of average-based combination rule, similarity-based combination rule, evidence distance-based combination rule, evidence-credit based combination rule and the proposed method are 0.84, 0.88, 0.88, 0.88 and 0.91. Experimental results show that the proposed method has higher accuracy of decision making and more reliable combination results, which can provide an efficient solution for decision-making based on evidence theory.