- From: Lars Marius Garshol <larsga@ontopia.net>
- Date: Fri, 24 Mar 2006 10:27:35 +0100
- To: SWBPD list <public-swbp-wg@w3.org>
* Pat Hayes > > Sorry, I have only just seen this thread. It only just started, so no worries. > RDF reification describes a stating (a particular instance, or > token, of a syntactic entity) which is about as far as one can > reasonably get from something semantic, which I gather from your > emails is what "reification" means in TM. Yes, this is my understanding, too. > Suppose the basic fact is that Bill and Sue are married. Then we > can distinguish > > 1. Married, which is a binary relation: in RDF/OWL, a property. > 2. The fact that Bill and Sue are married: in RDF/OWL, represented > by a triple. > 3. The particular state of being married that holds uniquely > between Bill and Sue (and no others): what in philosophy is often > called a 'trope' (see eg http://en.wikipedia.org/wiki/ > Trope#Tropes_in_philosophy). This has no standard RDF > representation, but it could be described, somewhat artificially, > as a subproperty of Married. (Described in OWL, this subproperty > would have singleton classes as its domain and range.) > 4. The RDF triple, considered as a platonic syntactic object, which > asserts (2). Again, there is no RDF equivalent, although some folk > use RDF reification for this (contrary to what the standard says; > but it does say it non-normatively) > 5. A particular token or inscription of this triple in some > document: this is what an RDF reification is intended to denote, > according to the RDF semantics. What we are after here is 2. or 3. I have to admit that I am clueless as to what the distinction between them is. The trouble may be that I don't see any difference between a fact of a marriage and the state of being married. I tried looking in Wikipedia, but, well, it didn't help. Any additional clues would be welcome. > This would seem to depend on what 'reification' means in TM. Can > anyone tell me how to find this out? The description in http:// > www.isotopicmaps.org/sam/sam-model/#d0e991 is completely > incomprehensible. It means either 2. or 3., but I don't yet know which. > BTW, a singular lack in this ISO TM document is an explanation of > what is meant by "relationship", as in [...] It's true that this is not defined beyond the use of a common English term. I understand that for the purposes of logic this is unlikely to be satisfactory. > This could be understood as meaning a relation, as in sense (1) > above, or a fact (or proposition) as in sense (2), or possibly as > meaning a trope, as in sense (3), or possibly something else > altogether. It is impossible for me to determine what the document > actually means, and the term is not defined in it anywhere. Can > anyone point me at an explanation of what this terminology > ("relationship") is intended to mean in TM? There is none. > A related question: is there any kind of formal semantics for TM? > Without one, no suggested mapping between TM and RDF can be > authoritative. There is no formal semantics for Topic Maps. I understand your concern that this means mapping from something that has no logical interpretation to something that does, but this happens to be the situation we are in. I think it's worth bearing in mind that this will be the case when mapping to RDF from pretty much any existing technology, so this is not a failing that's unique to Topic Maps. -- Lars Marius Garshol, Ontopian http://www.ontopia.net +47 98 21 55 50 http://www.garshol.priv.no
Received on Friday, 24 March 2006 09:27:37 UTC