- From: Pat Hayes <phayes@ihmc.us>
- Date: Fri, 24 Mar 2006 01:07:14 -0800
- To: "Steve Pepper" <pepper@ontopia.net>
- Cc: "Lars Marius Garshol" <larsga@ontopia.net>, "RDFTM editors" <rdftm@ontopia.net>, "SWBPD list" <public-swbp-wg@w3.org>
>[Regarding the issue of whether reification has the same >semantics in Topic Maps and RDF] Sorry, I have only just seen this thread. 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. > Basically, the use case is to be able to state marriages as a > single triple (for convenience, say), while still retaining > the ability to talk about the marriage, and retaining the > connection between the triple and the marriage node. Trying to understand this, it seems that there are several notions involved. Let me try to disentangle them, to help me understand what you want and how best to deliver it. 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 remains is to figure out how to express TM reification if we >| can't just use normal RDF reification. 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. BTW, a singular lack in this ISO TM document is an explanation of what is meant by "relationship", as in ----- 3.1 association representation of a relationship between one or more subjects ----- (from http://www.isotopicmaps.org/sam/sam-model/#terms-and-definitions) 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? A related question: is there any kind of formal semantics for TM? Without one, no suggested mapping between TM and RDF can be authoritative. Pat Hayes -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 cell phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Received on Friday, 24 March 2006 09:07:24 UTC