Comments about section 7.3.6, "Propositions, Situation Models, and Occurrences"
> “This is because many propositions describe a single situation
> (a "general situation model") that may have multiple occurrences.”
The paragraph containing this statement and the paragraph above are reworded by Mark. But this statement remains unchanged. If the statement is about a single general situation model, then it should not say “single situation”. Situations are not models. On the other hand, if it is about the single situation, it would be more clear to say that where a proposition corresponds to a single situation, that situation might occur at various other times than at the current time of the world for which the truth of the proposition is being considered.
> “For example, the proposition "rental car 123 is inspected", using a fact
> type "rental car is inspected", describes multiple occurrences if the rental
> car is inspected more than once.”
This is from Mark’s rewrite of paragraph 2.
The problem with the statement is that the proposition given as an example does not fully describe occurrences. It describes a circumstance that is included by multiple occurrences. Each of the occurrences is a situation that includes Rental Car 123 being inspected and that further includes some other circumstance that distinguishes one occurrence from the others, such as it being a certain time. It could be said that the proposition partially describes those occurrences.
> “In a temporal world, a logical sentence need not be true or false; it can be
> sometimes true and sometimes false, and therefore neither true nor false.”
This statement presumes the temporal world has no past/present/future. A “logical sentence” that is an interpretation of a natural language sentence about a world is considered to be true or false with respect to the current time in that world. Tense is used when describing past or future situations. There is no need to abandon truth-functional logic when temporal concepts are used. Indeed, time concepts are used widely and effectively in logic systems where “logical sentences” are either true or false, and never both, with respect to any world.
> “For example, the proposition "activity A precedes activity B for a given order"
”
This is unclear. But it might demonstrate the point made at the end of the same paragraph that the Date-Time submission might be misusing SBVR’s concept ‘proposition’. A more clear example would help us understand whether there is misuse or not.
> “
each of the occurrences of John actually writing a book.”
These words from an example in 12.3.6 (and similarly in 12.3.1) illustrate something missing from the Date-Time submission that, if provided, would help it to align with SBVR. According to the submission, there are occurrences of “John actually writing a book”. But the actual writing of a book by John is not a model. There are multiple occurrences of it and it is not a model, but an activity (a kind of state of affairs, or what Date-Time calls a “situation” in its clause 5.9). The Date-Time submission does not provide a fact type to relate a temporal occurrence to the activity, situation or circumstance that has the occurrence. That is unfortunate.
> “Brazil wins the FIFA World Cup.”
> “
both true and false, or neither, in a world that includes all of
> the last 20 years.”
The example under ‘proposition describes occurrence’ starts with an ambiguous statement. It is in present tense, so it either means that the winning is happening presently (the news bulletin at the final horn) or, by another interpretation, it means that Brazil wins from time to time: winning the FIFA World Cup is something that Brazil does. A world in which the current year is 2002 includes 1994 being in the past and excludes 1994 being the current year. The final statement describing the example seems to describe a world in which the present year is all of 20 different years, which is impossible. A possible world has one past, one present and one future. If the Date-Time submission abandons that fundamental idea, then it is no wonder that they claim that propositions are “both true and false, or neither”. It would be best to have a clear example and separates the ideas of whether a situation has been or will be actual from whether it is actual in the world under consideration. The truth of a proposition is based on whether the state of affairs to which it corresponds is actual. It is not based on how many times that state of affairs has occurred in that world’s past or will occur in that world’s future. I am not arguing against the fact type, ‘proposition describes occurrence’, which relates a proposition to occurrences across time. I am arguing against using a bad example to create confusion about how propositions are true or false.
> “The situation model is the bindable target of an objectification
”
I recall that there was already agreement to remove the statement above. Related notes were already corrected. A situation model is not a bindable target unless it is one of these: an individual concept, a variable or an expression. Also, a situation model is not a referent of a bindable target of an objectification unless it is a state of affairs.
> “The proposition “John is writing a book” is true during the time periods of each of the occurrences of John actually writing a book”
The proposition is true if John is writing a book. That’s all. The situation of John’s writing a book is actual if John is writing a book. That situation might be actual at different times, but other propositions would refer to those other times. E.g., “John was writing a book in 2010”, which is true or false on its own that’s a different proposition. The primary failure in the thinking behind this section is the failure to recognize that a proposition corresponds to just what the proposition proposes and no more. The explanation of the example fails to explain how occurrences are distinguished, and therefore, fails to show how the proposition “John is writing a book” describes any of them other than that it describes one circumstance included in each of them. The proposition gives no indication of whether occurrences are distinguished by book (if John is writing multiple books, perhaps simultaneously) or by place (if writing on different devices) or by contiguous time interval (if John interrupts writing to eat dinner). Perhaps the verb phrase should be changed to “indefinitely describes” or “partially describes”.
Proposed Resolution:
(These changes were adopted by the submission team after the final submission. They are recorded in this Issue for reconsideration by the FTF).
Replace the first two paragraphs of 7.3.6 with the following:
In a possible world that has no notion of time, there is a 1-to-1 relationship between propositions and states of the possible world: A proposition is true if the state it describes is the state of that world, and it is false if the state it describes is not the state of that world. SBVR truth semantics reflect this model.
When temporal concepts are introduced into the formal logic model, a distinction must be made between two aspects of the SBVR concept ‘proposition’ a 'meaning' that is either true or false, and that corresponds to at most one situation. This is because many propositions describe a single situation (a "general situation model") that may have multiple occurrences. For example, the proposition "rental car 123 is inspected", using a fact type "rental car is inspected", describes multiple occurrences if the rental car is inspected more than once.
Under "proposition describes situation model":
Delete the Definition that reads " The situation model is the bindable target of an objectification that considers a closed logical formulation that means the proposition."
Delete the Example that reads " The proposition “John is writing a book” is true during the time periods of each of the occurrences of John actually writing a book."
Change the date in the Example that reads " It is true in the world of 1998 ..." to read "1994".