- From: Sandro Hawke <sandro@w3.org>
- Date: Sun, 20 Mar 2011 09:58:12 -0400
- To: Pat Hayes <phayes@ihmc.us>
- Cc: RDF Working Group <public-rdf-wg@w3.org>
On Sat, 2011-03-19 at 20:29 -0500, Pat Hayes wrote: > On Mar 19, 2011, at 7:16 PM, Sandro Hawke wrote: > > > On Sat, 2011-03-19 at 19:02 -0500, Pat Hayes wrote: > >> On Mar 18, 2011, at 3:56 PM, Sandro Hawke wrote: > >> > >>> On Fri, 2011-03-18 at 19:22 +0000, Andy Seaborne wrote: > >>>> > >>>> Is g-snap->g-text is just a function of the content type? > >>> > >>> Well, probably, for our purposes, I think so. > >>> > >>> There's a trivial case where it's not: the arbitrary non-semantic > >>> variability in serialization, eg whitespace. So, some notion of > >>> equivalence class of g-texts may be important. > >> > >> Can't we simply *define* g-texts to be equivalent under such trivial variations? It is our notion, after all. > > > > I'm not quite sure what you mean. I think it's important the g-text be > > a subclass of character or byte strings, so *equality* is string > > equality. > > Well, that kills my suggestion right there. So let me push back on this point. Why do you think this is important? Why should a g-text not have its own g-style notion of equality? Why should it be a subclass of byte strings? Strings are very real to me (as for most programmers, I suspect), and having g-texts be strings is very comforting. I could probably get used to some other abstraction (as I have with RDF graphs), but there would still be strings being transmitted down the wire, which I would sometimes need to pay attention to, so I'd still need a notion of strings-representing-graphs in addition to whatever might serve this equivalence/equality purpose. I suppose we could give that abstraction a name and see if it's useful -- maybe a g-coding? But I can't actually see how I would use that, and where it would sit between graphs and strings. (Okay, of course strings don't really exist, and I'm using a wireless connection, but I think that just proves my point, that strings are an abstraction I'm terribly familiar with. They feel real, and introducing a different-but-similar abstraction would confuse me. It feels a bit like you're proposing we defines something like "Cat" (in the normal sense of the word, a domestic feline), but such that all cats born on the same day are the same cat. That's too weird for my brain.) > > For equivalence, yes, it seems like there's a simple and > > obvious meaning of equivalence, but I don't know how to formalize it, > > You did later in the message :-) Indeed. :-) Why is it this group does most of its interesting email during non-work hours, even when you account for the time zones of the members? (this is sequitur because during work hours I would have put more time into re-writing the email.) -- Sandro > I guess my overall question is, why do we need to distinguish identity from equivalence? Maybe this question is a residue from when I used to think like a mathematician, but I'd be interested in your answer. > > Pat > > > and I maybe it's not that quite that simple, for example: > > > > g-text t1: '_:x <http://www.w3.org/2000/01/rdf-schema#comment> "Hello"' > > g-text t2: '_:x <http://www.w3.org/2000/01/rdf-schema#comment> "Hello"' > > g-text t3: '_:y <http://www.w3.org/2000/01/rdf-schema#comment> "Hello"' > > > > I think all of the are equivalent, but the equivalence of t1 and t2 > > (where the difference is just whitespace), seems somewhat different from > > that between either of them and t3 (where the difference is in blank > > node labeling). > > > > Should we just define a single standard "equivalence" of g-texts, or do > > we need to allow room for there being several different kinds? > > Why would anyone need different kinds? > > > > > Maybe the simple notion is "semantic equivalence" of g-texts, which I > > might define as: T1 and T2 are semantically equivalent iff the RDF > > graphs produced by correct parsing of either of them are > > indistinguishable. > > > > -- Sandro > > > >> Pat > >> > >>> > >>> There's a related problem I don't know if we can or should address, > >>> which is how to deal with websites which use cookies or other > >>> information (IP address, browser sniffing, etc) to customize content. > >>> > >>> Does AWWW deal with these at all? Not that I recall. > >>> > >>> For an RDF example, I could make it so http://hawke.org/ip returns > >>> something like > >>> > >>> { <> eg;currentClientIP "128.113.1.1" } > >>> > >>> ... but returning your actual IP address. Given the right cloudhosting > >>> infrastructure, I could meaningfully, and perhaps usefully, return two > >>> different non-equivalent g-texts (ie g-texts for different g-snaps), at > >>> the exactly same moment in time. > >>> > >>> So, I think the model of web addresses identifying g-box which contains > >>> one g-snap at any point in time is as good as REST, and probably good > >>> enough, but still not perfect. > >>> > >>> -- Sandro > >>> > >>> > >>> > >>> > >> > >> ------------------------------------------------------------ > >> 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 > >> > >> > >> > >> > >> > >> > > > > > > > > ------------------------------------------------------------ > 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 > > > > > >
Received on Sunday, 20 March 2011 13:58:21 UTC