THE DATA ADMINISTRATION NEWSLETTER – TDAN.com
ROBERT S. SEINER – PUBLISHER

Printer-friendly

E-mail to friend

Business Rules – May 2010

Rustling Up Good Definitions: There’s a Lot Less and a Lot More to It Than You Think

Published: May 1, 2010

How long should a good definition be? Should definitions include specifications about business functions and/or constraints? How should these kinds of specifications be handled? This issue’s column takes an in-depth look at the long and short of definitions.

A good definition for a business concept must be both short and long. Fundamentally, it should focus only on the core essence of the concept – so it should be short. Yet specification of how the concept functions in the business – its relevance – is also important. So too is knowing what constraints do and do not apply to it. So it should to be long. Short? Long? What’s right?! Let’s look at some real-life examples to sort things out.

Definitions and Rule Statements

Consider the following definition created by business people concerning electrical power grid operation.


This definition says more than it needs to. The essence of the business concept is simply “Party that purchases Energy to satisfy Load.” That is really all the definition should say. Yet the remainder of the content is also clearly important. What should become of that? Here is a two-part answer.

1. In the real world there is no obviously no way (using current know-how) for a Load to get Energy unless it is connected to the grid. That constraint should be expressed as a separate rule, as follows.
   
   
   Rule: The Load for which an End-User purchases Energy is always directly connected to the Electric Power Grid or to a Distribution System.
   
   
   
2. What about reselling Energy? This business actually has another term (Load-Serving Entity) for Parties that do resell Energy. Consequently, we can extract the following rule from the original definition.
   

Note that this constraint eliminates possibilities. Under this rule, for example, an End-User could never be a landlord that charges tenants for the electricity they use – precisely the case in this business. The rule so indicates, and is therefore a valid discriminating characteristic of End-User.

Representing the two constraints above as separate rules has important advantages.

• Business people can focus on the essence of concepts, rather than on real-world constraints.
• An appropriate syntax (e.g., RuleSpeak^R) can be used to express the rules improving their precision and consistency. 
• The constraints can participate more directly in quality analysis (e.g., for discovery of anomalies).
  

All too often in real-life business vocabularies, we see long, jumbled definitions, in which the embedded logic is virtually unparsable. Definitions should be short, concise and clear. “Extra” semantics can be handled as rules.

Definitions and Advice Statements

Another important opportunity related to definitions is illustrated by a second example, which was also created by business people concerning electrical power grid operation.


From this definition, one might assume (wrongly) that all Network Components either generate or transmit Power. How is this important bit of definition-related knowledge to be expressed? Clearly, it is not something you would want to embed in the definition. Instead, it can be expressed as an advice.


From a business perspective, advices are useful for several crucial reasons. Remember that large-scale business rule initiatives involve many different people over long periods of time.

• To officially recognize that the issue has been discussed and resolved – that is, that there is actually no rule.
• To make such knowledge explicit so it can be verified (hopefully, in mechanistic fashion).
• To provide guidance to people outside the initiative, perhaps ones not even very familiar with the business.
  

Definitions, Rules and Advices

We now have two senses of “definition” – the small, specific sense (the core essence), and the large, aggregate sense (a definition and all related rules and advices).

Definitions picked at random from the dictionary do not indicate separate rules and advices. For example, consider Webster’s definition of the word “maverick.”


It is important to put this definition into perspective.

• It was created by definition professionals, not by business people. So we would certainly hope it would be a well-formed one!
• It was not created to run an actual ranching-and-cow business, to specify business rules or business strategy related thereto, or to encode any associated knowledge. Real-life business rule initiatives, of course, must attend comprehensively to all these needs. 
• It depends on the definitions of other terms (“branded,” “range” and perhaps “animal”) undoubtedly also defined by Webster’s. So the “essence” of its semantics is complete in that aggregate sense.
  

The definition does, however, add this interesting bit: “esp. a motherless calf.” What is that, and how should it be represented? Bundled into the definition? In a real-life business, we need to provide a more direct means to capture it, which we can do in an advice.


To take the example further, we must go beyond the point where the dictionary leaves off. For example, why would the ranching-and-cow business be interested in the notion of mavericks? We can state the probable reason as a rule:


Note that piece of knowledge is not within the essence of “maverick.” It should not be embedded in the definition. Nonetheless, it is obviously still important guidance.

The Long and Short of Definitions

When business people form definitions, they tend to put way too much into them, especially concerning business function and/or constraints. The rustler rule above is an example of business function – in other words, why mavericks are relevant to the business. That should clearly not go into the definition.

An example of a constraint is the following.


Although a discriminating characteristic for maverick, this constraint should not go into the definition either. When it comes to definitions, short is good.

Note, however, the significant business knowledge this example rule reflects: (a) Branding a calf less than two months old tends to cause fatal infections (and therefore economic loss). (b) Rustlers know a calf still so dependent on its mother is unlikely to survive on its own, so it is not worth rustling. So when it comes to business know-how, long is good, but with the “long” expressed as rules and advices.