Monday, October 18, 2004

Date and Pascal on RDF

ON METADATA, RDF AND RELATIONAL REPRESENTATION and ON RELATIONAL BINARY DATABASE DESIGN.

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.

No comments: