Dòng Nội dung
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A Probabilistic Relational Database Model And Algebra / Nguyen Hoa // Tạp chí Tin học và Điều khiển học = Journal of Computer Science And Cybernetics . - 2015. - P. 305-321. - ISSN:


17 p.
Ký hiệu phân loại (DDC): 510
This paper introduces a probabilistic relational database model, called PRDB, forrepresenting and querying uncertain information of objects in practice. To develop the PRDB model,first, we represent the relational attribute value as a pair of probabilistic distributions on a set formodeling the possibility that the attribute can take one of the values of the set with a probabilitybelonging to the interval which is inferred from the pair of probabilistic distributions. Next, onthe basis representing such attribute values, we formally define the notions as the schema, relation,probabilistic functional dependency and probabilistic relational algebraic operations for PRDB.In addition, a set of the properties of the probabilistic relational algebraic operations in PRDB also are formulated and proven.
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Region-Based Approximation of Probability Distributions : for Visibility Between Imprecise Points Among Obstacles / Kevin Buchin, Irina Kostitsyna, Maarten Löffler, Rodrigo I. Silveira // Algorithmica. - Springer US. - Vol. 81, Issue 7 (Jul. 2019) p.2682-2715. - ISSN:



Ký hiệu phân loại (DDC):
Let p and q be two imprecise points, given as probability density functions on R2,and let O be a set of disjoint polygonal obstacles in R2. We study the problem ofapproximating the probability that p and q can see each other; i.e., that the segmentconnecting p and q does not cross any obstacle in O. To solve this problem, we firstapproximate each density function by a weighted set of polygons. Then we focus oncomputing the visibility between two points inside two of such polygons, where wecan assume that the points are drawn uniformly at random. We show how this problemcan be solved exactly in O((n + m)2) time, where n and m are the total complexitiesof the two polygons and the set of obstacles, respectively. Using this as a subroutine,we show that the probability that p and q can see each other amidst a set of obstaclesof total complexity m can be approximated within error ε in O(1/ε3 + m2/ε2) time.
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