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  1. OMG Issue

DTV_ — "Law of Monogamy" example is poorly stated

  • Key: DTV_-11
  • Legacy Issue Number: 16663
  • Status: closed  
  • Source: Google ( Don Baisley)
  • Summary:

    Regarding the "monogamy" example in clause 7.3
    > “Consider the law of monogamy as it exists in some countries:”
    > “It is prohibited that a person1 is married to person2, if that person1 is married to another person3 and person2 is different from person3.”
    > “This rule is not entirely correctÂ….”
    I cannot imagine a country with the law of monogamy stated like that. It is not proper English nor is it proper SBVR SE. How about this: “A person must not be married to more than one person.” This section argues that the rule statement is “not entirely correct” because it doesn’t say “at the same time”. But that is nonsense. Based on that argument, every rule would need to explicitly tie every relation it uses to time. E.g.:
    Rule A: It is prohibited that a drunk driver operate a EU-Rent vehicle.
    Rule B: It is prohibited that there exists a time interval such a driver is drunk throughout that time interval and the driver operates a vehicle throughout that time interval and the vehicle is a EU-Rent vehicle throughout that time interval.
    It would be better to point out that in any situation there is at most one present time. Therefore, the law of monogamy stated as “A person must not be married to more than one person” is perfectly correct and it logically implies that “A person must not be married to more than one person at the same time.”

    “occurrence” is defined in the introduction to be a possible state of affairs. This is OK, if that’s what is intended. But “occurrence” is defined differently later.

    Proposed Resolution:
    Change the text at the start of the clause from:
    Consider the law of monogamy as it exists in some countries:
    It is prohibited that a person is married to more than one person.
    This rule is correct only on the understanding that the rule is evaluated at a point in time, as specified in this document. A version of the rule that uses the concepts defined in this section to make this understanding explicit is:
    If a person1 is married to some person2 occurs for some time interval, it is prohibited that person1 is married to another person3 during the time interval.

    to:
    Consider the law of monogamy as it exists in some countries:
    It is prohibited that a person is married to more than one person.
    This rule is correct only on the understanding that the rule is evaluated at a point in time, as specified in this document. A version of the rule that uses the concepts defined in this section to make this understanding explicit is:
    If a person1 is married to some person2 occurs for some time interval, it is prohibited that person1 is married to another person3 during the time interval.

  • Reported: DTV 1.0b1 — Wed, 16 Nov 2011 05:00 GMT
  • Disposition: Resolved — DTV 1.0
  • Disposition Summary:

    Chose a different example from EU-Rent that illustrates the point. Add a new Rationale section that discusses in more detail different techniques for writing rules that refer to situations and time. Add new verb concepts 'occurrence1 overlaps occurrence2' and 'situation model1 overlaps situation model2' to simplify rules that talk about two situation models occurring at the same time.

  • Updated: Sun, 8 Mar 2015 17:51 GMT