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Decision Table Processing

IP.com Disclosure Number: IPCOM000076422D
Original Publication Date: 1972-Feb-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 33K

IBM

Related People

Davis, RA: AUTHOR

Abstract

A decision table is a tabular arrangement of various possible combinations of input variables and the action that is to be taken in response to each of the combinations of input variables. Known tables have been made up of a condition stub, a set of rules, and an action stub. The condition stub defines the various possible states of inputs to the table. Each rule shows a particular group of input variables for which a particular action is appropriate. In the execution of a decision table, the condition stub is used to establish which variables apply to the problem and the variables are compared with the rules to find a match. The action stub tells the appropriate action to be taken.

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Decision Table Processing

A decision table is a tabular arrangement of various possible combinations of input variables and the action that is to be taken in response to each of the combinations of input variables. Known tables have been made up of a condition stub, a set of rules, and an action stub. The condition stub defines the various possible states of inputs to the table. Each rule shows a particular group of input variables for which a particular action is appropriate. In the execution of a decision table, the condition stub is used to establish which variables apply to the problem and the variables are compared with the rules to find a match. The action stub tells the appropriate action to be taken.

It is now suggested to include a routine called a driver that executes the decision table. The driver is independent of the decision table and can be used with various different tables. When a problem program reaches the point where a decision table is to be executed, it calls the driver and identifies the selected decision table.

The decision table shown in the figure includes a condition stub, a set of rules, and an action stub. The rules include a care mask, a rule mask, and an action mask. Each of the five blocks in the decision table represents a series of addressable entries. The entries in the condition stub and the action stub are, for the most part, instructions. The three blocks of the rules are aligned horizontally in the figure to show that a rule is made up of a care mask, a rule mask, and an action mask, and that the three entries that make up a rule are at consecutively addressable locations. The condition stub comprises of series of instructions for logical operations on the inputs to the table to form the condition mask. Generally, the inputs will...