@INPROCEEDINGS { Rsds3799,
author = {Nakamura, Akira}, 
title = {On a Rough Logic Based on Incomplete Knowledge Systems}, 
booktitle = {Soft Computing}, 
conference = {International Workshop on Rough Sets and Soft Computing}, 
pages = {36--39}, 
publisher = {The Society for Computer Simulation}, 
address = {San Diego, U.S.A.}, 
month = {November}, 
year = 1994, 
editor = {Lin, Tsau Young and Wildberger, A.M.}, 
isbn = {1-56555-077-3}, 
abstract = {This paper presents a modal logic based on incomplete information which are a kind of rough logics. Originally, the rough logic was constructed upon the knowledge system of complete in formations. In this paper, we treat incomplete knowledge representation systems in which information functions are nondeterministic. First of all, we consider the concept of completions of incomplete information proposed by Lipski. On the base of this completion, we define the usual equivalence relations. Then, we propose the definitions of upper and lower approximation operations for incomplete information system. After that, we examine some properties of these aerations. Finally, further problems are remarked.}, 
keywords = {rough sets, knowledge representation, logic, soft computing, }, 
}