Re: General semantics
Date: Fri, 21 May 2010 03:16:42 -0700 (PDT)
On 21 mei, 07:57, Clifford Heath <n..._at_spam.please.net> wrote:
> paul c wrote:
> > By unary relation I mean a relation with one attribute (which I think is
> > pretty standard lingo, surprised that anybody here wouldn't think that)
> Right, that's what I thought you meant. In which case, it could be a
> representation of either an existential fact type (an object type),
> or a unary predicate over one. The distinction is important. A unary
> predicate creates a subset of the object type it involves.
> This distinction was, I believe, the cause of your earlier disagreement.
> Further, a unary fact type does not have to be mapped as a unary relation.
> It could be represented as a boolean value in a table of that object type.
> > but I have no idea what a 'fact type' is. I know of relation and tuple
> > types but don't know what use terms like 'fact type' or 'unary fact'
> > terms might have.
> Fact oriented modeling has a parallel history with relational modeling.
> It's built on logic rather than sets; those are two sides of one coin.
> Needless to say, it has its own terminology - I tried to introduce some.
> It's a different perspective, equal in power and purity to RM. It has
> some advantages in mapping to natural language somewhat better. Seehttp://ormfoundation.orgfor more details. Ignore it, or look into it,
> but don't scoff at it until you've looked into it.
Looking at the TOC, I see that in the field of constraints, the book distinguishes between uniqueness constraints, value constraints, subset constraints, equality constraints, exclusion constraints, ring constraints, join constraints, ...
That is not an approach that invites to read on.
The RM really has all that is needed to be able to (de facto) do factoriented modeling : relvars having predicates, plus the CWA.
SIRA_PRISE records the predicate of each relvar in its catalog. The predicate of the catalog relvar that does this, is "<relvarname> is a relvar whose predicate is <predicate>.". SIRA_PRISE also has a method that can generate sentences from this predicate, e.g. the sentence "RELVAR is a relvar whose predicate is "<relvarname> is a relvar whose predicate is <predicate>.".". Incidentally, and referring to the subtitle of that website, the name of the method that does this is getTheFacts().
And I never needed any sort of ORM stuff to achieve that.
Nor did I need to make artificial distinctions between the predicates of unary catalog relvars (e.g. "<typename> is a DBMS-supported type.") and the others. Received on Fri May 21 2010 - 12:16:42 CEST