New SBV issue: Distinguishing the senses of infinitive and present tense
From Don Baisley
There are many verbs for which the present tense of a verb conveys a particularly different sense than the infinitive. The difference I refer to is not about "the present time", but about "occurring at least occasionally". For example, the statement that "Pam surfs" (present tense) combines the meaning of "to surf" (the infinitive) and the meaning that “it happens at least occasionally”.
For such verbs, there is a challenge when using SBVR's typical pattern of defining verb concepts in the present tense. It tends to conflate the infinitive sense of a verb with the different sense meant by the present tense. That conflation causes problems. This is not an issue for ORM or other approaches that do not try to support natural language tense in a generic way. The problem has no apparent impact for many verbs where the present tense sense of "occurring at least occasionally" is inconsequential or inapplicable. The problem is especially troublesome for eventive verbs. Most SBVR verbs are stative, so the problem has tended to go unnoticed in the SBVR vocabulary itself.
If supporting tense in a generic way, in logical formulations, the other tenses should be built on objectifications that start with the infinitive sense of a verb, not with the present tense. Also, modal operations like obligation build on the infinitive sense.
For examples below, I define verb concept forms for generic "tense" concepts using the verb "occurs" (where the there is a role that ranges over the concept 'state of affairs'). The choices of signifier and form are arbitrary (not necessary), but seem to convey the sense of the tenses naturally.
'person surfs' (present tense)
'person surf' (the infinitive sense)
Where someone puts 'person surfs' in a business glossary, there is an underlying verb concept that has the sense of "to surf", the infinitive. I show it here in examples as 'person surf' (leaving out the infintizing "to"). This underlying verb concept is necessary to correctly formulate other tenses, and even necessary to formulate use of the present tense in some cases, which I will show later.
Here are several examples of statements and interpretations using generic tense concepts built on the verb "occur". To be terse, I show objectification using brackets.
[Pam surf] occurs
Pam is surfing.
[Pam surf] is occurring
Pam was surfing.
[Pam surf] was occurring
Pam has been surfing.
[Pam surf] has been occurring
[Pam surf] occurred
Pam will be surfing.
[Pam surf] will be occurring
Pam will surf.
[Pam surf] will occur
Pam will have been surfing.
[Pam surf] will have been occurring
The second example above, "Pam is surfing", can serve to illustrate the need to build on the infinitive rather than the present tense sense. To build on the present tense would be to say the thing that “is occurring” is Pam surfing at least occasionally, which is incorrect. The present continuous and other tenses do not include the present tense sense of occurring at least occasionally, so they cannot rightly be built upon a concept that conveys that sense.
I said above I would show where the infinitive sense is sometimes needed even for the present tense. Here is a case where the infinitive 'person surf' concept is needed to formulate a statement that uses "surf" only in the present tense:
Pam talks while she surfs.
Wrong Interpretation I1: [Pam surfs] occurs while [Pam talks] occurs
I1 misses the key sense of the statement, because [Pam surfs] (present tense) means that surfing is something Pam does at least occasionally and [Pam talks] means that talking is something that Pam does at least occasionally. I1 applies 'state of affairs1 occurs while state of affairs2 occurs' to the wrong states of affairs (the states in which Pam occasionally surfs and Pam occasionally talks).
Right Interpretation I2: [[Pam surf] occur while [Pam talk] occur] occurs
I2 correctly factors out the tense and applies it at an outer level (as we often do with modal operations). The conjunction joins objectifications of the underlying sense of "to surf" and "to talk" without the added meaning of the present tense (that the surfing or talking is at least occasional). The sense of present tense (happening at least occasionally) is then added at the outside where it applies to the simultaneous actions.
SBVR does not prevent verbs concepts from being defined in glossaries in the infinitive , as is typical of dictionary definitions of verbs. That approach has always been available. But that approach is not used in SBVR’s own glossary and examples. In general, the sense of “occurs at least occasionally” is absent from SBVR’s own verb concepts, so the distinction is unimportant. But business rules and facts run into the problem. E.g., a EU-Rent rule about whether a renter smokes vs. a rule about whether he is smoking when in a rental car.
It will be best to resolve this in a way that does not disturb the business-friendly approach of showing verb concept readings in the present tense. It might be possible to define a pattern in SBVR Structured English by which verb concepts with an infinitive sense are implied where present tense versions are explicitly presented in a glossary.
Examples of formulations need to show the distinction. Existing examples should be examined and fixed as needed. New formulation examples might be helpful to demonstrate using generic tense concepts to build on a root verb concept.
None of this changes the meaning of 'state of affairs' or 'objectification', but understanding this issue and its solution might help bring clarity to some of the examples that have been discussed.