In order to improve the quality of web search,a new query expansion method by choosing meaningful structure data from a domain database is proposed.It categories attributes into three different classes,named as concept attribute,context attribute and meaningless attribute,according to their semantic features which are document frequency features and distinguishing capability features.It also defines the semantic relevance between two attributes when they have correlations in the database.Then it proposes trie-bitmap structure and pair pointer tables to implement efficient algorithms for discovering attribute semantic feature and detecting their semantic relevances.By using semantic attributes and their semantic relevances,expansion words can be generated and embedded into a vector space model with interpolation parameters.The experiments use an IMDB movie database and real texts collections to evaluate the proposed method by comparing its performance with a classical vector space model.The results show that the proposed method can improve text search efficiently and also improve both semantic features and semantic relevances with good separation capabilities.
Many data sharing applications require that publishing data should protect sensitive information pertaining to individuals,such as diseases of patients,the credit rating of a customer,and the salary of an employee.Meanwhile,certain information is required to be published.In this paper,we consider data-publishing applications where the publisher specifies both sensitive information and shared information.An adversary can infer the real value of a sensitive entry with a high confidence by using publishing data.The goal is to protect sensitive information in the presence of data inference using derived association rules on publishing data.We formulate the inference attack framework,and develop complexity results.We show that computing a safe partial table is an NP-hard problem.We classify the general problem into subcases based on the requirements of publishing information,and propose algorithms for finding a safe partial table to publish.We have conducted an empirical study to evaluate these algorithms on real data.The test results show that the proposed algorithms can produce approximate maximal published data and improve the performance of existing algorithms.
