Normal Number

Intent

Convert a plural subject (and its verb) to singular.

Motivation

People often express ideas as generalizations. Generalizations often use plural subjects. Plural subjects indicate collections, categories or classes. However, a plural subject often hides the true cardinality of the verb in a sentence. How many objects does a verb relate to its subject? The answer to this question helps determine the cardinality of the relationship (or action) expressed by a verb.

Applicability

Use normal number for a subject-verb combination when

you've extracted a statement with an isolated subject and an isolated verb,
but you discover that the subject has a plural number.

Considerations

Plural subjects often obscure the cardinality of the relationship expressed by a verb. Also, a finite verb must agree with the number and person of its subject (subject-verb agreement). Thus, for a third person singular subject with a present tense verb, the verb must also be singular. Consider the following examples:

storage buildings store chemical drums (plural subject + verb)
a storage building stores chemical drums (singular subject + verb)

staff buildings house staff members (plural subject + verb)
a staff building houses staff members (singular subject + verb)

Object-oriented designs focus on relationships and collaborations between individuals. Object-oriented designs often use a basic metonymy as a source of design components: a single instance represents an entire category or class of individuals. So, a statement about a single individual is applied to all the instances of a class. Thus, object-oriented designers often use sentence subjects and objects as candidates for class names.

Consequences

A normal form sentence has a singular subject and a singular verb with a complete predicate, active voice, indicative mood, affirmative polarity, and appropriate tense.

After conversion, a sentence subject refers to a single instance using a singular noun or noun phrase. Converting the subject to singular often exposes whether the verb relates the subject to a single or to multiple instances of the direct and indirect objects in a sentence.

Notice that you can use an indefinite article (a or an) to indicate that the subject is an instance of a class. Also, notice that an indefinite pronoun (each) can be used to retain a stronger indication that the subject is a member of a collection.