
200 Chapter 5 rough SetS and BayeS’ theorieS
Let us set the approximation parameter b to 0.6. The objects with value
1 or any value greater than or equal to 0.667 for attribute Y
1
belong to the
b-positive region of set Y
1
. On the other hand, the objects with value 0 for
attribute Y
1
belong to the b-negative region of set Y
1
. When generating the
decision rules, some condition values in the information system may be
unnecessary. We can remove as many unnecessary condition attributes as
possible without losing any essential information that can be retrieved from
the table. Thus, we can obtain the reduct table shown in Table ...