268 Chapter 9 Soft Computing SyStemS
The pair W
0
= (E,P ) is an approximation space of E. Its relational struc-
ture is induced from E.
W
0
= (W
0
,N,R,G)
W
0
is called an approximation world.
For any given two observable worlds, W
h
, W
k
, we can define a binary
relationships as follows: For each element x in W
h
, x belongs to at least one
of the R-elementary sets, say, H
i
, In this H
i
, there is a unique y in W
k
. The
set of such pairs (x,y) forms a binary (equivalence) relationship that relates
the two possible worlds.
9.9.4 Rough Models
A rough model (Lin, 1996) is a six-tuple
RM = (E,N,R,F,RO,W )
where:
E1. is a set of entities with a partition
N2. is a set of distinguished entities
R3. is a set of relationships
F4. is a set of partial functions ...