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In this paper, we propose OBMAC, an enhancement for medium access control (MAC) protocol based on the overhearing technique in wireless sensor networks (WSNs). In this type of networks, sensors are spatially correlated and they often sense and send the same information to the sink. Therefore, sensors waste energy in transmitting redundant data. Here, we(More)
The ETL (extract, transform and load) processes are responsible for the extraction of the data from the external sources, transforming the data in order to satisfy the integration and cleanness needs and for loading the data into the data warehouse. In the data mining field, there is a special concern on using the metrics for efficient classification(More)
  • Victor Felea
  • 2009
In this paper we define a new notion of containment for two queries, called strong containment. The strong containment implies the classical containment. A necessary and sufficient condition for the strong containment relation between two queries is given. The time complexity of the decision problem for two queries to be in strong containment relation is a(More)
In this paper we consider views expressed as unions of conjunctive formulas, where predicates of literals are views or database relations. The negation is allowed in the body of views. We assume that the variables occurring in the head of a view also occur in this body. Moreover, in case all variables occurring in negated atoms also occur in positive ones,(More)
The problem of counting satisfiability, i.e. count the number of satisfying assignments for a SAT problem, is used successfully in a number of problems. For example, it can provide heuristics for guiding planning and search, where an estimation of the probability for a given search would help lead to a goal. Counting satisfiability is a valuable approach(More)