- From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
- Date: Thu, 23 Aug 2012 12:25:46 +0200
- To: Pat Hayes <phayes@ihmc.us>
- CC: Richard Cyganiak <richard@cyganiak.de>, RDF Working Group WG <public-rdf-wg@w3.org>, Simon Reinhardt <simon.reinhardt@koeln.de>
Le 23/08/2012 07:55, Pat Hayes a écrit : > > On Aug 22, 2012, at 4:58 PM, Richard Cyganiak wrote: > >> On 13 Aug 2012, at 18:29, Antoine Zimmermann wrote: >>>> Note that the new Introduction section in the RDF Concepts ED >>>> contains an *informative* sentence that introduces the term >>>> “property” [4], and it is in line with RDF Semantics: >>>> >>>> [[ The predicate itself is an IRI and denotes a binary >>>> relation, also known as a property. ]] >>> >>> This is not what the RDF semantics says. A predicate denotes a >>> resource that must be in IP, the set of properties in the >>> interpretation. Resources in IP are associated with a binary >>> relation via the extension function IEXT. This is an important >>> distinction since this is what allows RDF to talk about >>> properties, classes, etc as instances. >> >> Ah, right. I forgot about the class/property extension stuff in RDF >> Semantics. >> >>> If predicates were denoting binary relations, the following would >>> be RDFS-inconsistent, when it is, in fact, RDFS-consistent: >>> >>> :p rdf:type xsd:string . :s :p :o . >> >> Do I get this right? This would be inconsistent because the first >> triple says its a Unicode string, and the second triple entails >> that it is a property, and hence (if my phrasing above were indeed >> correct) a binary relation. And a Unicode string is not a binary >> relation. >> >> And in reality, as RDF Semantics defines things, the second triple >> only entails that the Unicode string *has a property extension*, >> and the property extension is a binary relation. Hence, no >> contradiction. Anything can have a property extension. >> >> Right? > > Right. In RDF, in fact, everything *does* have a property extension > (whether you are using it or not, it is there to be used.) In this it > follows ISO Common Logic, by the way. Nope. From RDF Semantics 2004, Section 1.3: "3. A mapping IEXT from IP into the powerset of IR x IR i.e. the set of sets of pairs <x,y> with x and y in IR ." only elements of IP, aka properties, have a property extension. > >> >>> This is a proposal to replace the wording in section 1.2 [1]: >>> >>> "The predicate itself is an IRI and denotes a property, that is, >>> a resource that defines a binary relation." >> >> As usual, given that this is informative introduction text, there >> is a balance to be found between accuracy and simplicity. So I'd >> like to toss this around a bit. >> >> Is it accurate to say that the resource "defines" a binary >> relation? In what sense does it do that? > > Good point. > >> >> Wouldn't it be slightly more accurate (but perhaps less >> understandable) to say that the predicate IRI denotes "a property, >> that is, a resource that can be interpreted as a binary relation"? > > Yes. Or more accurately still, "...which is being interpreted as > a...." . > >> >> How about the fuzzy but perhaps simpler: "The predicate IRI denotes >> a property, that is, a resource that can be thought of as a binary >> relation." > > Better, I agree. Good, I agree with this too. > >> >> Or: "The predicate IRI denotes a property, that is, a resource that >> can be formalized as a binary relation." > > Nah, that suggest a misleading direction to push intuitions. I like > the previous idea. > >> >> I note that the overall purpose of the sentence is just to >> introduce the term "property" and give readers a decent intuition >> of what the term means. From that point of view, I still quite like >> the current phrasing ("The predicate IRI denotes a binary relation, >> also known as a property.") even though I know it's technically >> inaccurate. May I claim "harmless abuse of terminology" here? > > I think you can, yes. After all, people *can* read the actual > semantics if they want to get the details absolutely right. :-) Yes, but I like the fact that RDF Concepts explains what the concepts actually means such that it reduces the need to refer to the semantics. RDF Concepts 2004 was missing a bit in that respect. AZ. > > Pat > >> >> Best, Richard >> >> >>> [1] 1.2 Resources and Statements. >>> http://dvcs.w3.org/hg/rdf/raw-file/default/rdf-concepts/index.html#resources-and-statements >> >> > >>> > ------------------------------------------------------------ IHMC > (850)434 8903 or (650)494 3973 40 South Alcaniz St. > (850)202 4416 office Pensacola (850)202 > 4440 fax FL 32502 (850)291 0667 > mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes > > > > > > -- Antoine Zimmermann ISCOD / LSTI - Institut Henri Fayol École Nationale Supérieure des Mines de Saint-Étienne 158 cours Fauriel 42023 Saint-Étienne Cedex 2 France Tél:+33(0)4 77 42 66 03 Fax:+33(0)4 77 42 66 66 http://zimmer.aprilfoolsreview.com/
Received on Thursday, 23 August 2012 10:26:12 UTC