The ORM Foundation

Get the facts!

Search

Page 1 of 12 (115 items) 1 2 3 4 5 Next > ... Last »
  • Re: Model elements that are not displayed on any diagram

     NORMA allows an ORM schema to be displayed on many pages. The same model element may be displayed on many pages. It can be convenient to remove some shapes from a page to better focus that page on a specific subarea of the overall schema. There's probably little practical value in removing the final shape of a model element if you want ...
    Posted to NORMA (Forum) by Terry Halpin on Wed, Mar 11 2015
  • Re: Role value constraints in ORM2

     Yes, that's correct. I added role value constraints to ORM 2 in the mid 1990s. Before that, they applied only to object types. Cheers Terry 
    Posted to ORM Techniques (Forum) by Terry Halpin on Tue, Aug 12 2014
  • 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 Fri, Mar 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 Thu, Mar 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 Wed, Mar 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 Wed, Mar 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 Tue, Mar 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 Mon, Mar 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 Mon, Mar 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 Sun, Mar 16 2014
Page 1 of 12 (115 items) 1 2 3 4 5 Next > ... Last »
© 2008-2014 The ORM Foundation: A UK not-for-profit organisation -------------- Terms of Service