Re: 1 NF
Date: Thu, 1 Mar 2007 08:32:26 -0600
"-CELKO-" <jcelko212_at_earthlink.net> wrote in message
>>> the relation that contains the combinations of parts ever shipped in one
>>> or more shipments, a set of sets if you will. <<
> This is not 1NF in most cases be a single attribute because each part
> has meaning in the data model. YOu teally do want to look at them. To
> make 1NF atomic you would need a data model in which the lowst unit is
> the shipment -- a container level model.
>>> If it is a single attribute relation, then it may be hard to display
>>> without some device such as a "generated key". <<
> You would usually have a shipment number that might be derived from
> source, destination, etc.
>>> If certain relations we can imagine are not possible in Codd's RM
>>> without an arbitrary number of attributes then I'd think that his theory
>>> is broken. <<
> The theory is still good; modeling is hard.
> And not everything fits into RM. Documents and text searching require
> semantics and return a fuzzy revelance match number. Pictures are
> even worse. A human can look at a political cartoon, a symbol
> (Doonsberry's floating war helment) and a photogrpah and know that
> they are all George Buch. There is no way to write a join for that
> kind of matching.
"It has emerged from a study of the use of language in argument and persuasion and it is based on the identification and examination of those parts of language, which are essential for these purposes. It is formal in the sense that it lacks reference to meaning. Thereby, it achieves versatility: it may be used to judge the correctness of a chain of reasoning (in particular, a "mathematical proof") solely on the basis of the form (and not the content) of the sequence of statements which make up the chain." http://www.amazon.com/Set-Theory-Logic-Robert-Stoll/dp/0486638294
" The use of anthropomorphic terminology when dealing with computing systems is a symptom of professional immaturity." http://www.cs.utexas.edu/users/EWD/transcriptions/EWD04xx/EWD498.html
"...no matter how desirable it is for computerized systems to fully understand user meaning (the interpretation expressed by external predicates), unless those predicates can be directly formalized, internal predicates-and thus, predicate logic/the relational model--are the best we can currently do to guarantee consistent mechanized inferences." http://www.tdan.com/sms_issue26.htm
-- AnithReceived on Thu Mar 01 2007 - 15:32:26 CET
> Fractals curves also have problems, since there is
> an infinite distance between any two points and you cannot determine
> if a point is inaide or outside of a closed fractal curve.