The ORM Foundation

Get the facts!

Search

Page 9 of 12 (114 items) « First ... < Previous 7 8 9 10 11 Next > ... Last »
  • Re: uniqueness constraints vs idetifiers

    Hi Rolemo In this example, EmpNr is the identifier for Employee. If you declare a reference mode for an entity type, that provides its preferred identifier. The expression Academic(.empNr) is short for the 1:1 mandatory existential fact type &quot;Academic has / is of EmpNr()&quot;. Cheers Terry
    Posted to User experience (Forum) by Terry Halpin on 10-20-2008
  • Re: elementary fact types and functional dependencies (FDs)

    Hi Rolemo Facts may be compound or atomic. Atomic facts can&#39;t be rephrased as a conjunction of 2 or more smaller facts without information loss (with the same objects involved). Atomic facts are either elementary facts or existentail facts. Elementary facts apply a logical predicate to one or more objects, e.g. The Country identified by the ...
    Posted to User experience (Forum) by Terry Halpin on 10-18-2008
  • Re: ternary fact types

    Rolemo Your ternray is correct as is. There are two constraints on it (a mandatory role constraint and a uniqueness constarint). When you combine the meaning of these constraints you obtain&nbsp;the meaning you were after (corresponding to a multiplicity constraint of 1 in UML -- we don&#39;t use UML&#39;s multiplicity constraint notation because ...
    Posted to User experience (Forum) by Terry Halpin on 10-18-2008
  • Re: Terry's paper "Object-Role Modeling: an overview"

    Dear Rolemo Yes a predicate reading may contain nouns. In ORM, it is up to you what you wish to think of as an object (I call this &quot;object relativity&quot;). A predicate reading in ORM is the same as in predicate logic, viz. a sentence with object placeholders in it. You can phrase the sentence and choose the objects how you wish. ...
    Posted to User experience (Forum) by Terry Halpin on 10-18-2008
  • Re: values vs entities

    Dear Rolemo In this case we chose to identify ranks by rank codes (e.g. &quot;SL&quot; for Senior Lecturer). We could instead have identified ranks by rank names (e.g. &quot;Senior Lecturer&quot;). Modeling it this way, we are&nbsp;talking directly&nbsp;about the ranks, rather than codes or names. I think this is&nbsp;probably how most people ...
    Posted to User experience (Forum) by Terry Halpin on 10-17-2008
  • Re: Terry's paper "Object-Role Modeling: an overview"

    Dear Rolemo There is more than one correct way to model information. If you want to model the fact f9 the way it was verbalized then the predicate reading should have been &quot;has professors in&quot; and the righthand object type would be Quantity, not PrfQuantity. Notice fact s f14 and f16&nbsp;are similar, except the predicate readings have ...
    Posted to User experience (Forum) by Terry Halpin on 10-17-2008
  • Re: orm notations misunderstanding

    To get started with NORMA, I suggest you work through the NORMA Labs that I uploaded to the ORM Foundation. You can find them in the Library. &nbsp; Cheers Terry
    Posted to User experience (Forum) by Terry Halpin on 10-15-2008
  • Re: can i use NORMA without VS?

    Currently you need at least the standard version of VS2005 or VS2008 to run NORMA. We are hoping that Microsoft will add one module that we requested to the free Express version of VS that would allow NORMA to run on that, but so far no decision has been made whether that will happen. In addition to VisioModeler, which is freely available, the ...
    Posted to Technical support (Forum) by Terry Halpin on 10-13-2008
  • Re: orm notations misunderstanding

    &nbsp;As Ken indicated, there are major problems with the UML multiplicity notation. Unlike ORM and Barker ER, UML combines the global notion of mandatory with the local notion of frequency in a single concept of multiplicity. While this&nbsp;works reasonably well&nbsp;for binary associations, it leads to all kinds of problems with n-ary ...
    Posted to User experience (Forum) by Terry Halpin on 10-13-2008
  • Re: Highlight "Select on Diagram"

    The model element is highlighted in a similar way as it would be if you selected it manually.I personally find this is enough, but I agree it would make it easier to spot if we added some other highlighting, such as color. I&#39;ll discuss this with Matt to see what is feasible. &nbsp; Cheers Terry
Page 9 of 12 (114 items) « First ... < Previous 7 8 9 10 11 Next > ... Last »
© 2008-2014 The ORM Foundation: A UK not-for-profit organisation -------------- Terms of Service