Special Evaluation Specifications for Decision Rules: How to Support Very Smart, Very Friendly Business Decision Systems
A breach occurs for a business rule when the business rule isn't satisfied upon being applied to some set of circumstances (state of affairs). Normally we think about breaches occurring for behavioral rules, where a breach means a violation has occurred (e.g., you violated the posted speed limit).
The potential for violations of behavioral rules raises several important questions that business analysts should answer in advance of deployment for each behavioral rule:
- What level of enforcement should be applied?
- What special response to a violation is appropriate, if any?
- What special message, if any, should be returned to some worker(s) upon a violation?
Unlike behavioral rules, no definitional rule can ever be violated. Literally, things must be correct under such rules by definition.
Let's take an example. Suppose somebody asserts "2+2=5". According to the rules of mathematics, we know the correct answer is 4. The answer "5" is deemed irrevocably wrong. But is the asserted answer ever allowed to stand?
- If the rule is defined as a decision rule, the asserted answer is never allowed to stand. More precisely, the assertion would never be recognized to have happened in the first place. If someone asserts "2+2" the answer "4" is concluded immediately. Period. No breach, no opportunity for error.
- If defined as a behavioral rule (one that is not strictly enforced), the asserted answer is allowed to stand, but a violation is recognized. How might that capability be useful? Suppose the error were made by a student in grade school. It might be quite useful for the student and/or a tutor to know about it immediately and automatically. Specifying an appropriate violation response can make such notification happen.
In business, of course, definitional rules can be far more complex. Nonetheless, your ability to respond in appropriate ways to the specific, selective circumstances where certain rule-related events occur — automatically and independently of processes — provides exactly the mechanism you need to support very smart, very friendly operational business decision systems.
Decision Rules and Breaches
Decision rules are a special kind of definitional rule involving implications (e.g., A implies B). They support inferences and determinations — identifying an appropriate outcome from among a set of alternatives.
Like all decision rules, definitional rules cannot be violated. They are simply deemed true by definition.
Purely from a business perspective, however, some assertions of fact(s) may make it appear that a breach-like event has occurred. I take pains to emphasize any such perception is purely from the business perspective, not from the perspective of logic. You perceive a breach of a decision rule simply because it's useful to do so, not because any true violation has occurred.
In evaluating some particular case (situation, set of circumstances, or matter of concern), for example, things might not follow the 'happy path'. Think of a breach of a decision rule as a bump in the road — a gap along the happy path.
Let's return to the three questions listed earlier. Although the first question about enforcement level obviously doesn't apply to decision rules, adjusted versions of questions 2 and 3 remain in play.
Consider the following simple business example. Suppose a bank has this decision rule:
A credit application must be considered discrepancy-free with respect to a credit report for the applicant if all the following are the same:
- date of birth
- Social Security Number
- current address
- previous address
Let's suppose that an applicant uses just the initial for her middle name on her credit application. If the credit report shows her full middle name, then the names are not the same and the credit application will not be considered discrepancy-free.
Note carefully the rule hasn't been violated; it did its 'work' correctly and it did reach the proper conclusion (not discrepancy-free). But a gap — a breach — for her case has been identified from a business perspective because the rule failed on one of the conditions. We should be able to take advantage of that breach to take appropriate action — selectively, automatically, and in real time.
For example, the desired response to the breach might be to insert the following to-do item in the work queue of the responsible staff member: "Review discrepancy and manually ok if appropriate." (The to-do item should naturally also provide ready access to the related documents.) The breach of the rule causes this action to occur automatically.
Think about how many decision rules might exist for determining credit-worthiness, and how many selective conditions they might have. Could you build a responsive system by incorporating the selective responses needed into the related process model(s)? Not a chance — that approach won't scale. Instead, the selective responses need to be specified based on the business-rule side of things.
Kinds of Breach Specifications for Decision Rules
Breach specifications for a decision rule can be of the following two kinds.
Breach Response. A breach response can be an action of virtually any kind. For example, a breach action might be to:
- add some task(s) to a (non-redundant) to-do list in some appropriate work queue.
- add some documentation items to a (non-redundant) not-yet-received list.
By these means, very selective follow-up processing/handling ("what to do next") can be organized pertaining to any specific issue (breach) for a given case. Such selectivity is made possible by the granularity of the rules.
Breach Message. A specially-worded breach message can be forwarded to any involved party, either inside or outside the company. A breach message generally explains one or both of the following at any level of detail desired:
- Why the rule or condition failed. (The rule or condition statement already indicates very precisely what the issue is, but the breach message can explain in a more friendly manner.)
- What should be done to address the issue.
More Complex Example
Breach specifications apply selectively and specifically to a decision rule and/or any of its conditions. A breach specification applies if and only if that decision rule and/or condition fails (is not true) in evaluating some specific case (e.g., a specific credit application). An example of a decision rule with condition-specific breach specifications is illustrated in Table 1.
|A fluctuating income must be considered eligible if all the following are true:||
Conditions of the
||Add to-do item for that credit application: "Contact employer to verify applicant has reasonable opportunity for future income.||
||Add required documentation items not yet received to a pending list for the credit application.||To applicant: "[date] Here's a list of documentation items related to your income we have not yet received. [pending list]."|
Using Breach Specifications
Breach specifications can be:
- general for an entire decision rule, including all its conditions. (The example in Table 1 doesn't include any whole-rule specifications. If the rule did, they would appear in the first row.)
- specific to a given condition.
- specific to collections of conditions (none shown for the example).
A breach is detected only if the conclusion of the rule as a whole, or some particular condition within it, evaluates to not true. Things being true should be viewed as moving the case along the desired path (i.e., no breach has occurred). Decision rules (and breach specifications) should be expressed carefully so as to preserve this positive orientation.
Generally, breach actions should be specified only if something can be done to overcome a failure (of a rule or condition). The goal is to move things forward in the case. In the example above, for instance, if nothing whatsoever can be done to correct an issue, the credit application should simply be declined. A behavioral rule to that effect should be specified.
In hierarchies of decisions (e.g., as in Q-Charts) and decision rules (e.g., as based on series of logical dependencies), breach specifications should generally be made only at the lowest level of rule reduction/decomposition. A rule at a higher level in a logical hierarchy only evaluates to not true if some rule(s) below it evaluate to not true. Define breach specifications at the lowest level of granularity.
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 Ronald G. Ross, "Breaking the Rules: Breach Questions," Business Rules Journal, Vol. 14, No. 2 (Feb. 2013), URL: http://www.BRCommunity.com/a2013/b688.html
 Ronald G. Ross, "What Is a Business Rule?" Business Rules Journal, Vol. 11, No. 3 (Mar. 2010), URL: http://www.BRCommunity.com/a2010/b525.html
 Ronald G. Ross, "Decision Rules vs. Behavioral Rules," Business Rules Journal, Vol. 14, No. 7 (July 2013), URL: http://www.BRCommunity.com/a2013/b709.html
 Although rules can be specified in violation specifications for behavioral rules (e.g., to express some sanction or penalty), they should never be specified within breach specifications for a decision rule. Such 'nesting' of rules, especially on the basis of 'not true', is inappropriate.
 By default, breach specifications for a decision rule apply only the first time it is evaluated for each case. The assumption is that all business rules, including decision rules, are evaluated on a continuous basis. Re-application of any breach specification for a case therefore requires additional timing and iteration criteria. Whether a case is evaluated iteratively on the same set of decision rules based on timing criteria applied by or for some external process or platform is outside the scope of this discussion. No matter what the scheme of evaluation, the expression of the decision rules — as for all business rules — should be completely unaware of it.
 Ronald G. Ross, "Modeling Decision Structures — Part 2: Question Charts (Q Charts™) and Hybrid Diagrams," Business Rules Journal, Vol. 14, No. 10 (Oct. 2013), URL: http://www.BRCommunity.com/a2013/b722.html
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