Writing Natural Language Rule Statements — a Systematic Approach Part 28: Verbs and Conditional Clauses
About this series of articles
While my first series of articles on writing natural language rule statements explored a wide variety of issues in a rather organic and hence random manner, this series takes a more holistic and systematic approach and draws on insights gained while writing my recently-published book on the same topic. Rule statements recommended in these articles are intended to comply with the Object Management Group's Semantics of Business Vocabulary and Business Rules (SBVR) version 1.0.
The story so far
In earlier articles in this series (see the "Language Archives" sidebar) we have looked at standardised rule statements for various types of operative rules (data rules, activity rules, and party rules) and definitional rules. Each specific type of rule statement has a common formulation which we have discussed in both a relatively informal way and by way of rule statement patterns.
In the previous two articleswe looked at some of the syntactic components that may be found in rule statements of all types, namely prepositional phrases,qualifying clauses, terms, and determiners. In this article we shall look at the two other common syntactic components, namely verbs and conditional clauses.
Establishing what is or is not a verb (or any other word class) can be a non-trivial exercise. The simplest way to distinguish verbs in English is based on the way they behave. Every English verb that is not a modal auxiliary exhibits the following two characteristics, which are only exhibited by verbs other than modal auxiliaries:
- It inflects, in that the form after a singular noun — 'he', 'she', or 'it' (e.g., is and specifies) — is different to the form after a plural noun or 'they' (are and specify, respectively).
- It has a form (the infinitive) that can follow a modal auxiliary (in particular must and may). Except for is/are (for which the infinitive form is be), the infinitive form of all verbs is the same as the form after a plural noun or 'they'.
English verbs may be used in a variety of ways, only some of which are permitted in rule statements in the constrained natural language I have been describing in these articles:
- Any given use of a verb is either:
- transitive, in that it requires not only a subject but at least one object, e.g., create, specify, prevent, (a person or thing cannot just create, specify, or prevent; he, she, or it must create, specify, or prevent something), or
- intransitive, in that it requires only a subject, e.g., exist, occur (a person or thing can just exist or occur but cannot "*exist something" or "*occur something").
Some verbs may be used transitively or intransitively, e.g., close as in "the door closes" and "the attendant closes the door."
The verb be is rather different to other verbs, and is now often referred to as being intensive or circumstantial rather than transitive, since the words following the verb are not an object distinct from the subject (as with other verbs) but a reference to another facet of the subject or to one of its qualities, characteristics, attributes (i.e., a complement), or its circumstance.
A rule statement can include transitive and/or intransitive verbs as well as the verb be.
- Rule statements use mainly the present tense form of a verb (e.g., specify) or (occasionally) one of the past tense forms (e.g., specified, have specified, had specified) rather than the future tense form (e.g., 'will specify'). Note that a past tense form is only used in rule statements that refer to activities or processes that have occurred prior to the data or activity to be tested by the rule, e.g.,
RS309. Each passenger
must board the flight for which that passenger has checked in
no later than 15 minutes before the departure time of that flight.
- Rule statements use mainly the simple form of a verb (e.g., specify, specified) rather than the progressive aspect (e.g., 'am specifying', 'was specifying'). Rule statements such as RS309 that refer to a previous activity or process may use the perfect aspect (e.g., have specified, had specified).
- Rule statements use the declarative mood (as in "the form specifies the departure date") rather than the interrogative mood (as in "Does the form specify the departure date?"), the subjunctive mood (as in "If the form were to specify the departure date, ….") or the imperative mood (as in "Fasten your seatbelts." or "Do not pass this point.").
- After a must or may, the infinitive form is required (as in "each application must specify a payment method"). In any other place in a rule statement, a third person form is used (e.g., "the application specifies a payment method", "the applications specify different payment methods").
- If the subject of a verb signifies the person or thing performing the action (the actor or agent), the active voice is used (e.g., presents as in "the passenger presents a boarding pass"), whereas if the subject of the verb signifies the person or thing on which the action is performed (the patient or target), the passive voice is used (e.g., is presented by as in "a boarding pass is presented by the passenger").
A similar distinction may be used for some verbs expressing relationships rather than actions, e.g., "the folder contains two files" and "two files are contained in the folder".
- For all verb forms starting with an auxiliary verb (is/are, has/have, must, may) negation involves the inclusion of not after the auxiliary verb. For example, is performed by becomes is not performed by, has run becomes has not run. Note there are other auxiliary verbs in general use but those listed are the only auxiliary verbs used in rule statements.
For most other verb forms, negation involves prefixing the infinitive form of the verb with does not/do not. For example, runs becomes does not run.
Apart from the passive form of a verb, there are other multi-word formulations that behave as verbs. These are known as compound verbs whereas most of the verbs we have encountered so far in this article are simple verbs.
- A preposition other than by can be used after be and a past participle (e.g., be associated with, be assigned to, be filed in, be registered on).
- An adjective can be used between be and a preposition, to form a phrase that behaves like a transitive verb (e.g., be responsible for, be similar to) or an intensive verb (e.g., be identical to, be equal to).
- An adjective or past participle can be used after be, to form a phrase that behaves like an intransitive verb (e.g., be present, be available, be excluded).
- A noun (with or without a preceding article) can be used with be and a preposition, to form a phrase that behaves like a transitive verb (e.g., be part of, be a category of, take the place of, be a match for).
- A noun can be used after be and a preposition, to form a phrase that behaves like an intransitive verb (e.g., be on duty, be in service).
- A noun and a preposition can be used after have to form a phrase that behaves like a transitive verb (e.g., have responsibility for).
- Many verbs (including be but not have) can be used with a preposition to form phrases that behave like transitive verbs (e.g., apply for, buy into, act as, check out, look up).
Some verbs can also be used with two prepositions (e.g., check up on).
Verbs such as state, ask, question, or check state or question the truth of a proposition, as in "The witness stated that he had not seen the assailant clearly", "I asked if this were true", "She questioned whether he could have done it", or "The flight attendant checked that all passengers' seat belts were fastened." In each of these, the verb is separated from the following proposition by a conjunction (that, if, or whether).
These are mandatory in mandatory option selection rule statements, data combination consistency rule statements, state transition constraint statements, party restriction rule statements, and optional in most other types of rule statement.
Each conditional clause consists of a subject and a predicate. The conditional clauses that follow are all from rule statements that have been included in this series of articles. Each is rendered with the subject of the clause on the first line and the predicate on the remaining line or lines:
- that driver
- that laptop computer
is not in a bag
- that passenger
checks in for that flight
- a defect notice
is current for that vehicle
- a cabin crew member
advises that electronic devices may be operated safely
- that timesheet
specifies a project code for each activity
- that person
holds a command endorsement that is current
- any file within that folder
is open for editing
- the customer who raised that order
is a preferred customer
- the quantity on hand of that part
falls below the reorder point for that part
- the current medical status of that person
- the age of that person
is at least 5 years
- the status that is currently recorded for that Loan Application
is Under Review
- the sum of the activity durations specified on that timesheet
is at least 40 hours
It can be seen that the subject of a conditional clause can be:
- a term signifying a real-world object (e.g., driver, passenger, timesheet) preceded by a determiner (typically the, a, an, or that) (as in examples 1 – 7)
- a term signifying a real-world object, preceded by a determiner and followed by:
- a prepositional phrase (e.g., within that folder in example 8) or
- a qualifying clause (e.g., who raised that order in example 9)
- a term signifying a property of a real-world object, preceded by a determiner and followed by:
- a prepositional phrase (e.g., of that part in example 10, of that person in examples 11 and 12) or
- qualifying clause (e.g., that is currently recorded for that Loan Application in example 13)
relating that property to that real-world object
- the verbalisation of an arithmetic expression involving one or more quantifiable properties of a real-world object (as in example 14).
The predicate of a conditional clause can take many forms, including:
- an intransitive verb (e.g., is intoxicated in example 1, is open for editing in example 8)
- a transitive verb followed by a determiner and a term (as in examples 2 – 4), which may in turn be followed by:
- a prepositional phrase (e.g., for each activity in example 6, for that part in example 10) or
- a qualifying clause (e.g., that is current in example 7)
- is followed by:
- a determiner and a term (as in example 9) or
- a literal (as in examples 11 and 13)
- any of the predicates described in Article 22 (e.g., the range predicates in examples 12 and 14)
- a verb followed by that, if, or whether, followed in turn by a proposition (which takes the form of a conditional clause) (e.g., advises that electronic devices may be operated safely).
Predicates may be joined by and or or, e.g., holds an airline transport pilot license that is current
and a type endorsement that is current for each aircraft type to be flown by that flight crew.
Conditional clauses may also be joined by and or or, e.g., that product is out of stock and that order is urgent.
Note that every conditional clause must include at least one term from elsewhere in the rule statement, each preceded by the keyword that (e.g., driver in RS177, laptop computer in RS189, vehicle in RS190, passenger and flight in RS176).
must not operate any vehicle
if that driver is intoxicated.
|RS189.||Security screening of a laptop computer
only if that laptop computer is not in a bag.
must not be operated
if a defect notice is current for that vehicle.
may board a flight
only after that passenger checks in for that flight.
To be continued...
In the next article in this series I will look at quality criteria that should be applied to rule statements.
 The first of which is: Graham Witt, "A Practical Method of Developing Natural Language Rule Statements (Part 1)," Business Rules Journal, Vol. 10, No. 2 (Feb. 2009), URL: http://www.BRCommunity.com/a2009/b461.html
 Semantics of Business Vocabulary and Business Rules (SBVR), v1.0. Object Management Group (Jan. 2008). Available at http://www.omg.org/spec/SBVR/1.0/
The font and colour conventions used in these rule statements reflect those in the SBVR, namely underlined teal for terms, italic blue for verb phrases, orange for keywords, and double-underlined green for names and other literals. Note that, for clarity, these conventions are not used for rule statements that exhibit one or more non-recommended characteristics.
 A rule that defines a construct created or used by an organisation (or the industry within which it operates), or defines a property of such a construct, and which cannot therefore be contravened, by contrast with an operative rule.
 Graham Witt, "Writing Natural Language Rule Statements — a Systematic Approach — Part 26: Some Common Syntactic Components of Rule Statements," Business Rules Journal, Vol. 15, No. 9 (Sep. 2014), URL: http://www.BRCommunity.com/a2014/b777.html and
Graham Witt, "Writing Natural Language Rule Statements —a Systematic Approach —Part 27: Terms and determiners," Business Rules Journal, Vol. 15, No. 11 (Nov. 2014), URL: http://www.brcommunity.com/a2014/b785.html
 A phrase formed from:
• a preposition, such as for, from, in, of, on, to, or (in the case of a temporal constraint) after, before, during, earlier than, later than
• an optional determiner, such as a, an, any, each, that, the
• a term, such as passenger, credit card.
 A clause used after a term in two ways:
1. following the subject term of a rule statement, to restrict the scope of that rule statement to a subset of the set of objects signified by that term, rather than the set of all objects signified by that term (e.g., 'for a return journey' in "Each flight booking request for a return journey must specify exactly one return date.")
2. following any other term in a rule statement, to make a constraint more specific than if the qualifying clause were absent (e.g., 'that is current' in "Each passenger must present a passport that is current.").
 Statements of rules that place restrictions on who can perform some processes or activities or play some roles, based on age, some other physical characteristic or capability, or training, testing, and certification in the appropriate skills.
 Graham Witt, "Writing Natural Language Rule Statements — a Systematic Approach — Part 22: The Syntax of Some Data Content Rule Statements," Business Rules Journal, Vol. 15, No. 5 (May 2014), URL: http://www.BRCommunity.com/a2014/b762.html
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