Rules that Give You Too Much Freedom

Silvie   Spreeuwenberg
Silvie Spreeuwenberg Founder / Director, LibRT Read Author Bio || Read All Articles by Silvie Spreeuwenberg

Freedom should be removed by rules.  In fact, a rule that does not remove freedom in some way is not a rule according to the SBVR standard.  That being said, you may be confused by the title of this column.  Well, given this restriction on what a rule is and what you expect from a rule statement, there are still many ways to express such a rule.

RuleSpeak and SBVR's Structured English impose some restrictions on our use of language (see the box below), but due to the flexible nature of natural language you still have a lot of freedom ... consequently, we rarely see the same rule written in exactly the same way by different people using natural language.

There is a tendency to ask for a more restricted rule language to improve:

  • consistency in writing similar rules by different people,
  • consistent interpretation (non-ambiguity),
  • support for validation & verification,
  • translation to software systems.
RuleSpeak and SBVR restrictions

Every business rule statement must contain at least one business rule keyword.

The keywords in RuleSpeak are:

  • 'must'
  • 'only'

The keywords in SBVR Structured English are:

  • 'It is obligatory that'
  • 'It is necessary that'

Expressing rules as decision tables or decision trees greatly reduces your freedom of form but also your expressiveness.  So, when I need the expressiveness of natural language, I introduce very specific rule patterns to restrict my freedom and gain rigor.

Examples:

  • ... must be calculated as ....
  • A ... for ... must be calculated as ....
  • A <data element> for a <timeframe> and a <location> must be calculated as <formula>.

Each pattern is more specific, provides more guidance, and (consequently) less freedom.  The last pattern above is even specific to a particular domain.

Sentence patterns seem to be the fashion today.  They are not only popular for rules but also used in the descriptions of user stories in agile projects:  As a <role> I want <something> so that <benefit>.

Rules must decrease freedom and so must rule sentence patterns.  I am curious about the sentence patterns you use or recognize in your organization.  Please send me an e-mail with your examples at silvie@librt.com .

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Standard citation for this article:


citations icon
Silvie Spreeuwenberg , "Rules that Give You Too Much Freedom" Business Rules Journal Vol. 13, No. 6, (Jun. 2012)
URL: http://www.brcommunity.com/a2012/b656.html

About our Contributor:


Silvie   Spreeuwenberg
Silvie Spreeuwenberg Founder / Director, LibRT

Silvie Spreeuwenberg has a background in artificial intelligence and is the co-founder and director of LibRT. With LibRT, she helps clients draft business rules in the most efficient and effective way possible. Her clients are characterized by a need for agility and excellence in executing their unique business strategy or policy. Silvie's experience has resulted in the development of tools and techniques to increase the quality of business rules. She writes, "We believe that one should focus on quality management of business rules to make full profit of the business rules approach." LibRT is located in the Netherlands; for more information visit www.silviespreeuwenberg.com & www.librt.com

Read All Articles by Silvie Spreeuwenberg

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