The Conversion of Limited-Entry Decision Tables
to Optimal and Near-Optimal Flowcharts: Two New 
Algorithms

Two new algorithms for deriving optimal and
near-optimal flowcharts from limited entry decision 
tables are presented.  Both take into account rule frequencies
and the time needed to test conditions. 
 One of the algorithms, called the optimum-finding algorithm,
leads to a flowchart which truly minimizes 
execution time for a decision table in which simple rules
are already contracted to complex rules.  The 
other one, called the optimum-approaching algorithm, requires
many fewer calculations but does not necessarily 
produce the optimum flowchart.  The algorithms are first
derived for treating decision tables not containing 
an ELSE-rule, but the optimum-approaching algorithm
is shown to be equally valid for tables including 
such a rule.  Both algorithms are compared with existing
ones and are applied to a somewhat large decision 
table derived from a real case.  From this comparison two
conclusions are drawn.  (1) The optimum-approaching 
algorithm will usually lead to better results than comparable
existing ones and will not require more, 
but usually less, computation time.(2) In general, the
greater computation effort needed for applying 
the optimum-finding algorithm will not be justified
by the small reduction in execution time obtained.

CACM November, 1972

Verhelst, M.

decision table, flowcharting, preprocessor, optimal programs, search

3.50 3.59 4.19 4.29 4.49 5.31

CA721106 JB January 27, 1978  2:10 PM

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