- From: <jos.deroo.jd@belgium.agfa.com>
- Date: Mon, 13 Aug 2001 12:24:45 +0100
- To: sean@mysterylights.com
- Cc: www-rdf-interest@w3.org, www-rdf-logic@w3.org
that reminded me about http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0432.html but I really don't know at the moment... we really like N3! -- Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/ "Sean B. Palmer" <sean@mysterylights.com>@w3.org on 2001-08-11 01:38:12 AM Sent by: www-rdf-logic-request@w3.org To: <www-rdf-interest@w3.org>, <www-rdf-logic@w3.org> cc: Subject: NQuads In writing an inference engine, I found that reifying out tons of statements and statement sets (contexts) into NTriples was not only very frustrating on the part of the human that has to write it, but also quite difficult to process on the side of the tool. I wondered a) if it would be acceptable to separate data and inferences, and b) use two different formats for them. What I came up with, and what I have implemented, is NQuads. It's just NTriples, but instead of three terms, it has four. The fourth term is simply a context marker. Here's an example:- <#x> <#y> <#z> <#m> . <#z> <#y> <#x> <#n> . <#m> <#implies> <#n> <#a> . <#a> <#forAll> <#x> <#root> . <#a> <#forAll> <#z> <#root> . This is roughly equivalent to writing the following rule in Notation3:- { { :x :y :z } log:implies { :z :y :x } } a log:Truth; log:forAll :x, :y . The main difference is that all contexts have a URI. The question is what to use as a root context for the document. It is quite fair to come up with a URI that denotes the current "document" as a resource. The great thing about NQuads is that there is no guessing to the context for each of the triples: the author must state it explicitly. NQuads are totally convertible into NTriples, you just have to reify a lot. That's basically what it saves you: the reification. Note that the extra term is not a statement ID, it's a context ID. Thus, you can have stuff like:- <#x> <#y> <#z> <#m> . <#a> <#b> <#c> <#m> . See [1] for a rough translation of this using a model into NTriples. Now, using this format, I was able to write an inference engine in Python in just one day. It only handles contexts with single statements in the "old" context for now, but it can grok universally quantification and any number of statements in the "new" context. In short, NQuads are not going to be useful often, only when writing documents that have lots of contexts, for example rules files. But when you have those contexts, they save you a lot of time both writing and parsing because you're moving a certain amount of model into the syntax. And as the two are perfectly transmutable, there shouldn't be any inconsistencies except for the usual ratholes of what constitutes a "document" in NTriples and so forth. P.S. Please trim (if/any) replies according to topic. [1] Could be something like (substituting the de_facto terms of the season, such as the stuff in model.n3):- _:1 <#context> <#m> . _:2 <#context> <#m> . _:1 <#subject> <#x> . _:1 <#predicate> <#y> . _:1 <#object> <#z> . _:2 <#subject> <#a> . _:2 <#predicate> <#b> . _:2 <#object> <#c> . Perhaps you'd have another syntax for explicit statement IDs where you do a lot of reification? Hmm... but that would conflict with NQuads, unless you made NQuads NPents. Since I thought of this first, I'll assume that there is more need for it on the Semantic Web :-) cf. discussions about NQuads with Bijan et al. starting from "23:32:37" in:- http://ilrt.org/discovery/chatlogs/rdfig/2001-08-10.txt I also chumped some BLURB about it. -- Kindest Regards, Sean B. Palmer @prefix : <http://webns.net/roughterms/> . :Sean :hasHomepage <http://purl.org/net/sbp/> .
Received on Monday, 13 August 2001 06:25:21 UTC