Combining Decision Rules in a Decision Table
The techniques for minimizing logic circuits
are applied to the simplification of decision 
tables by the combining of decision rules. This method
is logically equivalent to the Quien-McCluskey 
method for finding prime implicants.  If some of the
decision rules implied in the ELSE Rule occur with 
low frequency, then the ELSE Rule can be used to further
simplify the decision table.  Several objectives 
merit consideration in optimizing a decision table:(1)
reducing machine execution time; (2) reducing 
preprocessing time; (3) reducing required machine memory;
(4) reducing the number of decision rules. 
 (This often improves the clarity of the decision table
to a human reader.)  It will be shown that objectives 
(3) and (4) can be furthered with the above methods.
 Objective (1) is also attained if overspecified 
decision rules are not combined.  Objective (2) must be
compared against the potential benefits of objectives 
(1), (3), and (4) in deciding whether to use the above methods.
CACM August, 1975
Shwayder, K.
