SBVR Speaks: (6) Concepts and Definitions in SBVR
In January 2008, the "Semantics of Business Vocabulary and Business Rules" (SBVR) was first presented by the Object Management Group (OMG) as an official specification of the OMG. Version 4 (SBVR 1.4) was published in 2017.
Rules are built on a foundation of defined concepts. In the Semantics of Business Vocabulary and Business Rules (SBVR) document itself, concepts (including verb concepts) are defined and expressed as terms and other symbols, and represented as vocabulary entries in SBVR Structured English. This month, we examine the basics of a vocabulary entry. Our focus is two-fold: first, to be able to read and understand the normative entries of the SBVR Standard itself and, secondly, to understand enough of the basics to be able to create our own vocabulary of entries in the style of SBVR Structured English (e.g., as in the EU-Rent vocabulary).
This article draws from SBVR Annex A — the informative material on SBVR Structured English. The examples presented are from the SBVR metamodel and from the EU-Rent case study (Annex G of SBVR). For an alternative, conforming style of writing concept definitions, see the companion article in this Issue of the Journal, which describes the RuleSpeak conventions for defining concepts.
A vocabulary is described in a document (or document section) having glossary-like entries for concepts that have representations in the vocabulary. Each entry is for a single concept, called the entry concept. Each entry starts with a primary representation as the headword — either a designation (term or name, for a noun concept) or a verb concept wording (for a verb concept).
Any of several kinds of captioned details can then be listed under the primary representation. A skeleton of some of the typical captions used for a vocabulary entry is shown below.
This article covers the following aspects of a basic vocabulary entry for a vocabulary-defined concept using the SBVR Structured English notation:
- Primary Representation
- Dictionary Basis and Source
- Examples and Notes
The Concept's Primary Representation: Designation or Wording
A vocabulary entry can be for any concept type. Its primary representation is shown in a font style that is appropriate to its type. For example, below are entries that are the designations for three noun concepts. The first two are terms (for general noun concepts) and the third is a name (for an individual noun concept).
branch agency Switzerland
The primary representation for a verb concept is a verb concept wording, consisting of a verb symbol and designations for the wording's one or more noun concept placeholders. In the unusual case where the same designation is used for more than one placeholder of the wording, a subscript on each placeholder can be used so that references to the roles from a definition or other text is unambiguous. For example, below are entries for two EU-Rent verb concepts (the second illustrating the use of subscripts to disambiguate its duplicate placeholder designations):
branch has car storage capacity date/time1 is after date/time2
It is recommended that quantifiers (including articles) and logical operators not be embedded within noun concept designations and verb concept wordings.
A definition is written as an expression that can be logically substituted for the primary representation. As a substitutable expression it is not a sentence and therefore does not end in a period.
A definition can be fully formal, partly formal, or informal. A definition is fully formal if all of its text is styled. A partially-formal definition starts with a styled designation for a more general concept but other parts of the text are unstyled, depending on an understanding of concepts external to this vocabulary.
Each of the different types of concept has a pattern for its definition.
Definition of a Noun Concept
A common pattern of definition begins with a designation for a more general concept followed by the keyword 'that' and then an expression of necessary and sufficient characteristics that distinguish a thing of the defined concept from other things of the more general concept. Another, less-used pattern also begins with a designation for a more general concept but then uses the word 'of' followed by another expression.
Two kinds of information are formally expressed by a fully-formal definition:
- a fact that the concept being defined is a category of a particular more general concept
- a closed projection that defines the concept
Only the first kind of information is formally expressed by a partially-formal definition. A partially-formal definition leads with a styled designation that is for a more general concept. That designation is generally followed by the keyword 'that' and then an informal expression of necessary and sufficient characteristics.
The following example shows a partially-formal definition. It formally expresses the fact that the concept 'corporate rental agreement' is a particular kind of 'contract', but it also uses words that are external to the locally-defined vocabulary.
|corporate rental agreement|
|Definition:||contract that establishes a negotiated set of rates under which a qualified corporate renter can rent a car|
The next example is fully formal. Its formal interpretation includes that EU-Rent's concept 'agency' specializes the concept 'branch', specifying what kind of branch it is in terms of its location and who it is operated by.
|Definition:||branch that is not located at a EU-Rent-owned site and is operated by some agent|
The next example (from EU-Rent) is not formal at all.
|Definition:||territory of a usually independent nation that is distinct as to name and the characteristics or attributes of its people|
Verbalizing the Definition of a Noun Concept
A definition of a noun concept can generally be read as a statement using the following pattern (where "a" represents either "a" or "an"):
A <designation> is a <definition>.
For example: An corporate rental agreement is a contract that establishes a negotiated set of rates under which a qualified corporate renter can rent a car.
Intensional vs. Extensional Definition
The formal definition shown above is an intensional definition. Another style of formal definition is extensional. The extensional style uses disjunction to combine a number of concepts. For example, a semantic formulation is anything that is a logical formulation or a projection, as the definition below states.
|Definition:||airport branch or city branch or agency|
Definition of an Individual Concept
A definition of a noun concept that is an individual concept must be a definite description of one single thing. It typically starts with a definite article (e.g., 'the'). For example:
|EU-Rent Enforcement Level Scheme|
|Definition:||the vocabulary that is owned by the EU-Rent English Community and that contains the enforcement levels of behavioral business rules|
The definition of an individual noun concept can generally be verbalized as a statement using the following pattern.
[The] <designation> is <definition>.
Here is the verbalization of the example given:
The EU-Rent Enforcement Scheme is the vocabulary that is owned by the EU-Rent English Community and that contains the enforcement levels of behavioral business rules.
Note that the leading 'The' in the verbalization is optional, depending on the designation. For example:
CRISIG is the vocabulary that is owned by The Car Rental Industry.
However, it is often the case that an individual concept has no definition at all because it is widely understood. In such a case the 'General Concept' caption can be used to clarify that this is a proper noun referring to the named thing. Here is an example.
Definition of a Verb Concept
A definition given for a verb concept is an expression that can be substituted for a simple statement expressed using a wording of the verb concept. The definition must refer to the placeholders in the verb concept wording. (This is done to relate the verb concept's definition to the things that play some role in instances of the verb concept.) Whether or not the definition is formal, each reference to a placeholder appears in the 'term' font and is preceded by the definite article 'the'.
Here is an example of an informally defined verb concept, followed by a fully-formal one.
|driver is responsible for rental|
|Definition:||the driver has personal contractual liability for the rental|
|car model specifies rental car|
|Definition:||the rental car has the set of style and feature properties of the car model|
Verbalizing the Definition of a Verb Concept
A definition of a verb concept can generally be read using the pattern below, which is shown for a binary verb concept but which works for verb concepts of any arity. (Note that "a" in the pattern represents either "a" or "an".)
A fact that a given <placeholder 1> <verb concept wording> a given <placeholder 2> is a fact that <definition>.
For example: A fact that a given driver is responsible for a given rental is a fact that the driver has personal contractual liability for the rental.
Similarly, the equivalence understood from a definition of a verb concept can generally be read using the following pattern:
A <placeholder 1> <verb concept wording> a <placeholder 2> if and only if <definition>.
For example: A driver is responsible for a rental if and only if the driver has personal contractual liability for the rental.
The General Concept caption
The 'General Concept' caption is used to designate the concept that generalizes the entry concept. This is not needed if the entry concept has a definition that starts with the general concept's term. But this caption can be useful in cases where a definition is not provided, as is often the case for individual concepts (named things) or for concepts taken from an external source. Here are two examples.
|General Concept :||country|
|Source:||CRISG ['rate group']|
Dictionary Basis and Source
Two captions are available to cite an external source that relates to a concept's meaning: the 'Source' caption and the 'Dictionary Basis' caption.
The 'Source' caption is used to indicate a source vocabulary (or other reference document) for a concept. The source's designation for the concept is given in square brackets and quoted after the name of the source; it might or might not match the entry's primary representation. If the source has a name for the concept itself, the name is given in square brackets, unquoted. The designation from the source is quoted if it is a term for the concept.
|source:||ISO1087-1 (English) (3.1.1) ['object']|
|Source:||CRISG (3.2.2) ['redeemed rental']|
The keywords 'based on' indicate the definition of the concept is largely derived from the given source but had some modification, as in the following example.
|Definition:||system of arbitrary signals (such as voice sounds or written symbols) and rules for combining them as used by a nation, people or other distinct community|
|Source:||based on AH|
This caption labels a definition from a common dictionary that supports the use of the primary representation. The entry source reference (written in the 'Source' style described above) is supplied at the end of the quoted definition. A dictionary basis should not be interpreted as an adopted definition. For example,
|Definition:||contract with a renter specifying use of a car of a car group for a rental period and a car movement|
|Dictionary Basis:||contract for use of a rental car by a renter for an agreed period under the rental company’s terms and conditions for rental [CRISG (1a) 'rental']|
Examples and Notes
Two additional, frequently-used captions are the 'Example' caption and the 'Note' caption.
The 'Example' caption labels examples involving the entry concept. For example,
|Definition:||undesirable occurrence during a rental that is the fault of one of the drivers|
|Example:||speeding offence, unpaid parking fine, damage to car caused by careless driving|
A 'Note' caption is used to label explanatory notes that do not fit within the other captions. For example:
|rental has pick-up branch|
|Note:||If the renter wishes to change the pick-up branch of a rental, EU-Rent regards it as a cancellation and a new rental.|
An entry concept provides the primary representation for a concept. However, a concept is not limited to a single representation. When there are additional designations or wordings for a concept, the 'Synonym' or 'Synonymous Form' caption (respectively) is used.
A synonym is another designation that can be substituted for the primary representation of a noun concept. It is a designation for the same concept. The examples below show two terms (i.e., synonyms) for one concept having one definition. The preferred symbol is given as the primary representation. The additional symbol is given using the 'Synonym' caption.
|Definition:||request that has been accepted by EU-Rent for an advance rental from a renter|
Where the primary representation is not a preferred representation for the entry concept, the 'See' caption introduces the preferred representation. No definition is given in this case. For example, the following entry creates a reference to the primary term for the concept.
|vehicle identification number|
The 'Synonymous Form' caption is used for a verb concept entry to provide an alternate wording in addition to the entry's primary wording. The order of placeholders for roles is often different in the verb concept's various wordings, but the meaning is the same since each represents the same verb concept.
A synonymous form clause is not typically written if the synonymous wording is simply a passive form of the primary wording. The following example shows a synonymous form that simply reverses the order of roles. Because the synonymous form is only a passive form of the primary wording, this would usually not appear as an explicit clause.
|car model specifies rental car|
|Synonymous Form :||rental car is specified by car model|
A synonymous form does not necessarily use the same designations for placeholders as are used in the primary representation. A placeholder might or might not use a designation for a role. When this happens, in order to match the placeholder of the synonymous form to the corresponding placeholder in the primary representation, the placeholder in the synonymous form is followed by the placeholder's designation in the primary representation in square brackets.
The example below shows two wordings for the same verb concept. One is expressed
in terms of a role (
the other is not.
|person has driver license|
|Synonymous Form :||driver license is for driver [person]|
If the same term is used for multiple placeholders, then subscripts can be used to distinguish them.
|period1 is before period2|
|Synonymous Form:||period2 is after period1|
In this instalment we have looked at the fundamentals of defining concepts, the basis for business rules. Next time we will examine some of the metamodel elements for concepts and definitions.
 Semantics of Business Vocabulary and Business Rules (SBVR). Object Management Group. The current version of SBVR is available on the OMG site.
 The car rental examples come from EU-Rent, a (fictitious) car rental company. This popular case study was contributed to the SBVR effort by Model Systems and appears in detail as Annex G of the SBVR document.
 Ronald G. Ross, "Concepts, Definitions, and Rules: RuleSpeak® Practices," Business Rules Journal, Vol. 7, No. 5 (May 2006), revised (Oct. 2013), URL: http://www.BRCommunity.com/a2006/b288b.html
 The styling used in definition expressions is described in SBVR Annex A and was described in the previous instalment. See "SBVR Speaks: Notations for Business Rule Expression," Business Rules Journal, Vol. 7, No. 4 (Apr. 2006) revised, URL: http://www.BRCommunity.com/a2006/b286.html
 The keyword 'that' used in definitions is the second sense defined for 'that' in the "A.1.2 Other Keywords" section of Annex A. The use of the word 'of' is also explained in the "Other Keywords" section of SBVR Annex A. These were also covered in previous instalments of SBVR Speaks.
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