Re: Demo: Modelling Cost of Travel Paths Between Towns

> > Then why do you keep bring up hardware bits with respect to
> > redundancies at the logical layer of data modelling?
>
> Because I'm trying to show that dabbling over storing the same letter or
> the same word twicce in a database is exactly as nonsensical as dabbling
> over storing a string of bits twice.

That representing a thing (ie a person, a string or a symbol) twice at the logical layer of the data model is redundant has nothing to do with hardware (ie strings of bits). Just because a thing (ie a string or symbol) doesn't usually have properties, doesn't mean that duplicate strings and symbols aren't redundant. It is easy to verify redundant strings are redundant. Modifying one will corrupt your data. (You many want to reread the example dealing with Islamics taking over the world and wanting to reverse the spelling of all words in OT "A Normalization Question").

It is not as easy to see that a typical RM db has duplicate symbols. For example, in a TM/XDb2, there is only one symbol X in a db. One can add a property the symbol X. One can relate symbol X in any manner (ie "John.likes = 'X'" or find all things that like X via "%.like='X';"). In RM, how does one represent the symbol X following the RM methodology? How does one a add property to the symbol X? How does one make any arbitrarty relation involving symbol X. And which one of the many duplicate symbols X's does one add that property to if he could? Why can't one represent the symbol X the same way as representing the person john in RM? Because RM is a limited data model.

You can't see the obvious that representing john the person twice is redundant in the same manner as representing the string 'john' twice is redundant in the same manner as represting the symbol X twice is redundant. John, 'john' and X are all things. Representing any one of them twice in the logical layer is redundant. Received on Tue Nov 16 2004 - 07:11:49 CET