427 research outputs found
Rough Sets Determined by Quasiorders
In this paper, the ordered set of rough sets determined by a quasiorder
relation is investigated. We prove that this ordered set is a complete,
completely distributive lattice. We show that on this lattice can be defined
three different kinds of complementation operations, and we describe its
completely join-irreducible elements. We also characterize the case in which
this lattice is a Stone lattice. Our results generalize some results of J.
Pomykala and J. A. Pomykala (1988) and M. Gehrke and E. Walker (1992) in case
is an equivalence.Comment: 18 pages, major revisio
Matroidal and Lattices Structures of Rough Sets and Some of Their Topological Characterizations
Matroids, rough set theory and lattices are efficient tools of knowledge discovery. Lattices and matroids are studied on preapproximations spaces. Li et al. proved that a lattice is Boolean if it is clopen set lattice for matroids. In our study, a lattice is Boolean if it is closed for matroids. Moreover, a topological lattice is discussed using its matroidal structure. Atoms in a complete atomic Boolean lattice are completely determined through its topological structure. Finally, a necessary and sufficient condition for a predefinable set is proved in preapproximation spaces. The value k for a predefinable set in lattice of matroidal closed sets is determined
Matroidal and Lattices Structures of Rough Sets and Some of Their Topological Characterizations
Matroids, rough set theory and lattices are efficient tools of knowledge discovery. Lattices and matroids are studied on preapproximations spaces. Li et al. proved that a lattice is Boolean if it is clopen set lattice for matroids. In our study, a lattice is Boolean if it is closed for matroids. Moreover, a topological lattice is discussed using its matroidal structure. Atoms in a complete atomic Boolean lattice are completely determined through its topological structure. Finally, a necessary and sufficient condition for a predefinable set is proved in preapproximation spaces. The value k for a predefinable set in lattice of matroidal closed sets is determined
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