New approach in defining rough approximations

  • Authors:
  • E. K. R. Nagarajan;D. Umadevi

  • Affiliations:
  • Centre for Research and Post Graduate Studies in Mathematics, Ayya Nadar Janaki Ammal College, Sivakasi, Tamil Nadu, India;Centre for Research and Post Graduate Studies in Mathematics, Ayya Nadar Janaki Ammal College, Sivakasi, Tamil Nadu, India

  • Venue:
  • Transactions on rough sets XIV
  • Year:
  • 2011

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Abstract

In this paper, we discuss some algebraic structures of the set of all lower(B∇) and upper(BΔ) approximations defined through the basic map ϕ in the general setting of complete atomic Boolean lattice B. In fact, we prove that if ϕ is extensive and closed, then B∇ and BΔ are algebraic completely distributive lattices. A representation theorem for algebraic completely distributive lattices in terms of B∇ under the existence of an extensive and closed map ϕ is given. We also prove that if ϕ is extensive and symmetric, then B∇ and BΔ are complete ortholattices. A representation theorem for complete ortholattices in terms of BΔ under the existence of an extensive and symmetric map ϕ is shown. Further, we define a map ϕ induced from the basic map ϕ and study the properties of the rough approximations defined with respect to ϕ under various conditions on the basic map ↦.