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  • Re: What is a fact?

    Hi Ken Although I am not a fully fledged Platonist, I could be classified as one kind of realist, as the term is currently used in philosophy. Your quote from Russell (1920) where he treated a proposition simply as a declarative sentence represents a position that few philosophers (other than Epstein, apparently) would agree with nowadays. ...
    Posted to Philosophy (Forum) by Terry Halpin on 03-28-2014
  • Re: What is a fact?

    Hi Ken Sentences are linguistic, but propositions are not. Utterances are speech acts, not propositions. A proposition is what it is that is asserted when a declarative sentence is uttered or inscribed. Of course, to determine the precise proposition expressed by an utterance or inscription of a sentence, one has to know the relevant context of ...
    Posted to Philosophy (Forum) by Terry Halpin on 03-27-2014
  • Re: What is a fact?

     Hi Niels You are probably aware that communication act theory (formerly, and sometimes still, known as speech act theory) has been an active field of study for many years, with Austin and Searle being the main early contributors. For a concise overview, see http://en.wikipedia.org/wiki/Speech_act.  Your phylogenetics example reminds ...
    Posted to Philosophy (Forum) by Terry Halpin on 03-26-2014
  • Re: Spanning Role Value Constraint

     Currently, role value constraints apply only to single roles. Objectification can be a solution in some cases, but is not advisable in your example since there is no uniqueness constraint over the (A,B) role pair. If you have a real world example where you wish to apply a value constraint matching the pattern you show, please provide it and ...
    Posted to ORM Techniques (Forum) by Terry Halpin on 03-26-2014
  • Re: What is a fact?

     I basically agree with Niels on how to conceive of propositions. In philosophy, there are different schools of thought on the precise nature of propositions, but I subscribe to one of the more popular viewpoints that treats propositions as extra-linguistic entities that are are always true or false (and hence truth-bearers). Their truth or ...
    Posted to Philosophy (Forum) by Terry Halpin on 03-25-2014
  • Re: Exclusion constraints

     Hi Niels  If a person can work only once for a given organization, then you can objectify "Person worked for Organization" as Employment and attach functional fact types to it for valid and transaction start and end dates.    If a person can work multiple periods for the same organization (e.g. resign, then rehire ...
    Posted to Extensions to ORM (Forum) by Terry Halpin on 03-17-2014
  • Re: Exclusion constraints

    Hi Niels I use "period" to mean an anchored duration of time. In the example I gave, periods were closed (anchored at both start and end), so had start and end times (includes date and time of day). If we modify the example to open periods (e.g. each period has a start but in not necessarily an end) the modeling (including constraints) ...
    Posted to Extensions to ORM (Forum) by Terry Halpin on 03-17-2014
  • Re: Exclusion constraints

     Hi Niels  We are considering support of structured datatypes, that would be modeled explicitly as coreferenced types to facilitate easy conceptual access to their components. An example would be ComplexNumber defined using two relationships to one-dimensional numbers (one for the real part and one for the imaginary part). Conceptually, ...
    Posted to Extensions to ORM (Forum) by Terry Halpin on 03-16-2014
  • Re: Exclusion constraints

     NORMA doesn't yet provide graphical support for those two constraints. Nor does it directly support a temporal range data type. As discussed below, there are multiple ways (I show two ways) to model the basic scenario, but currently those constraints need to be added as textual constraints and implemented manually.  We added ...
    Posted to Extensions to ORM (Forum) by Terry Halpin on 03-16-2014
  • Re: Question on BBB exercise 3.3

    J is not a conjunction of facts (unlike "Brisbane and Sydney are in some Country" which may be rephrased as a conjunction of "Brisbane is in some Country" and "Sydney is in some Country". It simply means "Brisbane is in the same country as Sydney" -- you can't split this into two facts without loss of ...
    Posted to User experience (Forum) by Terry Halpin on 10-13-2013
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