Monday, October 18, 2004

Date and Pascal on RDF


From the later:
"Research papers abound from the Semantic, Topic Map and RDF camps that claim relational binary database design is the superset of n-ary or the true relational model.

The only reference to relational binary that I could find on your site was mentioned by C.J. Date in passing. He mentioned that Codd showed that n-ary and even 0-ary relations have unique and important properties that would in fact make n-ary the superset."

"The foregoing point notwithstanding, there are actually some pretty strong arguments in favor of making all base relations binary. Well, not binary exactly, but irreducible, rather; an n-ary relation is irreducible if it can’t be non-loss decomposed into two or more projections each of degree less than n. (In practice, irreducible relations often are binary, a fact that might account for part of the confusion I mentioned; however, some irreducible relations are not binary and some binary relations are not irreducible.) But the question of whether base relations should be irreducible is a database design question, not a relational model question."

From Good recent writings on data.

Another one, ON THE “SEMANTIC WEB”. I was going to say that in iTQL we don't return NULL but we do if the value is unconstrained. I was going to say that in SPARQL it doesn't return NULL but it does. I've been playing with REL as well, just to see how it performs certain queries too.
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