Re: sketch of an exposition

OK, you've convinced me I'm so incompetent around "reference" that
I've completely removed it from my next draft (which I hope to have
ready by this afternoon, in time for review before tomorrow's call).

The AWWSW plan has always been to talk first about web 'semantics'
(mainly GET/200) without getting into anything resembling semantics of
reference or model theory, then separately as a 'part 2' talk about
how URIs might come to {denote, designate, refer to} things - that's
the only way I can sort it all out. I should have stuck to that plan.

If you can refer me to your favorite philosophy of reference, I'd
appreciate it. I will need ammunition for my next round with Larry
Masinter. The best I have right now is Quine who says that shifting
the question from meanings of words to meanings of sentences is an
advance - and I'm not sure how to apply that idea in this context.

Jonathan

On Thu, May 20, 2010 at 2:15 AM, Pat Hayes <phayes@ihmc.us> wrote:
>
> On May 17, 2010, at 4:40 PM, Jonathan Rees wrote:
>
>> Apologies up front:
>>  - sorry it's rough and unformatted.  I'm trying out expository ideas
>> and terminology & wanted to get this out to you all for critique
>>  - topic not covered: metadata subjects (DC, FRBR, etc.); redirections
>>  - tell me which statements you disagree with! we thrive on
>> statements that are interesting enough that one can argue over them.
>>  - idle question: does every IR have a REST-representation?
>>
>> -Jonathan
>>
>> -------------------
>>
>> Axiomatic method = don't take anything for granted - if some result
>> can't be proved from axioms already stated, do not assume that it is
>> true.
>>
>> Assume a universe of discourse, which I'll call Thing.
>>
>> In formal treatments one needs a way to refer to (or name or
>> designate) things.  For this purpose we may use URIs, although other
>> notations may be useful too.
>
> So, immediate question: are these names also in the UoD? Are URIs Things? I
> suspect the answer has to be Yes, but that makes things more complicated and
> less 'standard' already, because standard FOL keeps names and things
> strictly segregated. (For a very good reason, to avoid paradoxes.)  Suggest
> that you USE names in the axioms which are distinct from the URIs, which
> should be treated as objects in the UoD. (In fact, you do this already, with
> things like 'T' and 'U'.)
>
>>
>> Reference is not objective; when a URI refers to a Thing it's
>> because someone has chosen to have it do so.
>
> Really? How is that choice manifested functionally? What if two people make
> different choices for the same URI? Lots of hard questions here.
>
> Seems to me that 'personal' choice is a red herring. What matters for any
> actual use of referential names is that some *community* of people has
> somehow conspired to use a name referentially among themselves.
>
>>
>> Reference does not imply any special knowledge of a Thing.
>
> True, though it might presuppose SOME knowledge.
>
>>  I can
>> talk about a thing without knowing eactly which thing I'm talking
>> about
>
> Thats a different point.
> (1) I can refer to X without knowing all about X
> (2) I can refer to X without knowing if I'm referring to X
>
> 1 is much more plausible than 2.
>
>> - for example, I might be communicating partial knowledge
>> (properties) that I received from someone else.
>
> Yes, but if we are communicating and I understand a name in the message to
> refer to X but you intended to refer to Y, usually we have a genuine
> MIScommunication. That is different from me misunderstanding something you
> say about X, while still knowing that it is X you are referring to.
>
>>  Reference is not
>> "identification".
>
> True, but thats a different point. God alone knows what 'identification' is
> supposed to mean.
>
>>
>> We'll suppose that (in any given conversation or context) a URI refers
>> to at most one Thing.
>
> Havnt you changed the rules by saying 'refer to' simpliciteur here? Surely
> according to the above, its the person doing the referring, not the URI. (OR
> maybe that particular use of the URI, by the person with the intent, is what
> refers...)
>
>> An agent may take a URI to refer to no Thing at
>> all, or refer to a Thing by multiple URIs, or not take any URI to
>> refer to some Thing.
>
> I don't follow this. What is the third option, exactly?
>
>>
>> If a URI U refers to some thing T then <U> is another name for T.
>
> I think you mean, if U refers to T then WE can use '<U>' as a name for T, in
> our axiomatic meta-theory. Right? You need to keep two sense of 'name'
> distinct. There are the names we are talking ABOUT - the URIs - and the
> names we are USING. They aren't the same idea.
>
> BIG ISSUE. You have not yet said what you mean by 'refer' here. This 'refer'
> is not the referential use of names in the axioms!  That is the relationship
> between our meta-names, things like "R" and "T" and "W", and the things in
> the UoD that they denote. This is a relationship between URIs (which are
> things, I presume) and other things, ie its a relationship between things in
> the UoD, so it needs to be axiomatized just like any other relationship.
>
>>
>> Some Things will be what we call 'REST-representations'.
>>
>>  For now think of them as being similar to HTTP 'entities' - they
>>  consist of content and a few headers such as media type.
>>  But we'll figure out the details later.
>>
>>  We don't assume that these REST-representations are 'on the wire'
>>  or associated with particular events or messages.
>>  We reserve the right to refer to them using URIs, but generally
>>  this will be unnecessary.
>
> Well, WE will certainly need to refer to them, but WE (ie, we writing the
> axioms) can use our names freely to suit our axiomatic purposes. You use "R"
> just below to refer to a REST-representation, for example. (No URIs visible
> anywhere here.)
>
>>
>> Posit a relationship, which I'll call 'W', between some Things and
>> some 'REST-representations' e.g. W(T,R).
>>
>>  The intent is for W to capture what gets written variously
>>    R is "an entity corresponding to" T (RFC 2616 10.2.1)
>>    T "corresponds to" R (RFC 2616 10.3.1)
>>    R is a representation of the state of T (Fielding and Taylor)
>>    R "encodes information about state" of T (AWWW glossary)
>>    R "is a representation of" T (AWWW 2.4)
>>
>>  We permit the same REST-representation to be W-related to multiple
>>  Things, i.e. W(T,R) and W(T',R) is consistent with T != T'.
>>
>>  We permit one Thing to be W-related to more than one
>>  REST-representation, i.e. W(T,R) and W(T,R') is consistent with
>>  R != R'.
>>
>>  If you don't accept web architecture as expressed in RFC 2616 in
>>  its rudiments, you should stop reading here.
>>
>> Let us stipulate that a GET/200 HTTP exchange expresses a
>> W-relationship between a Thing and a REST-representation.  That is:
>>  1. If a URI U refers to a Thing <U>, and
>>  2. an HTTP request GET U results in a 200 response carrying
>>    REST-representation R, then
>>  3. we will interpret the exchange as communicating W(<U>, R).
>
> Well, OK, but I still want to know what the first condition means. Right
> now, this is essentially vacuous since 'refers to' could mean anything.
>
>>
>>  WHETHER WE CHOOSE TO BELIEVE W(<U>, R) IS ANOTHER STORY.
>>  (Consider a buggy or malicious proxy.  HTTPbis starts to address
>>  believability by trying to specify a notion of 'authority'.)
>>  ISSUES OF TRUST AND AUTHORITY WILL BE TREATED SEPARATELY (if we get
>>  around to it).
>
> Good.
>
>>
>>  We might fudge this by speaking of "credible" HTTP exchanges without
>>  saying exactly what that means (as indeed one cannot say).
>>
>> The implication goes in only one direction: a credible GET U/200 R
>> exchange implies W(<U>, R), but the absence of such an exchange does
>> not imply that W(<U>, R) is not the case.
>>
>> In fact there may be other ways to communicate or infer W(<U>, R) -
>> by consulting a cache, for example.
>>
>> A consequence (or precondition) of this stipulation is that for each
>> URI U for which there is a GET/200 exchange, there exists a Thing <U>
>> that U refers to.  Roughly speaking, all web URIs refer to
>> *something*.
>
> That isn't a consequence of the rule given above, and I don't see why its a
> precondition. If U doesnt refer to anything, then the first IF condition of
> the rule is false, so the rule is trivially satisfied.
>
> However, it is plausible, so why not stipulate it? You are writing the
> axioms, after all :-)
>
>>
>>  This is the way in which the web is "grandfathered" into the
>>  semantic web.
>>
>>  Although it's not falsifiable, this seems to be the idea that IH
>>  denies (there are no resources).
>>
>> This is a powerful constraint.  Since servers are "authoritative",
>> they can produce whatever 200 responses they like for a URI that they
>> control, and not violate protocol.  That is, for an *arbitrary* set of
>> REST-representations concoctable by a server, we've committed to
>> allowing the existence of a Thing that has those REST-representations.
>
> We aren't committed yet, but maybe we should be. But why does this apply to
> any *set* of REST-reps?  Nothing in the rule given refers to such sets.
> Seems to me you have a lot more axioms to write before this can be proven.
>
>>
>> Note on what is NOT provable at this point
>>
>>  We haven't created a way to falsify any W-statement.  That is,
>>  there is no way to infer the W(T,R) does not hold.  Therefore this
>>  theory is satisfiable by having a single Thing T, that all URIs
>>  refer to, having the property that W(T,R) for all
>>  REST-representations R.
>>
>> Note on time
>>
>>  Although W is time-sensitive, we'll ignore time as it is not
>>  helpful to account for it right now.  later we'll redo the
>>  treatment to take time into account.
>>
>>  So W is OK as a binary relation for now.  Later it might be
>>  W(X,R,t).
>
> Or it can still be binary, but X can be timesliced:  W(s(X, t), R). I would
> recommend this as a stronger (more expressive) way to deal with time.
>
>>
>> Note on RDF
>>
>>  RDF is just a vector for FOL, and FOL is a lot easier to read and
>>  think about, so better to start with FOL and then render it in RDF
>>  (and perhaps other notations) later on.
>
> Hmm. RDF is way weaker (less expressive) than FOL. But whatever, I suspect
> it doesnt really matter. We are using at least negation and implication in
> the axioms already, and implicitly using universal quantifiers. So we are
> using FOL.
>
>>
>> No number of GET/200 exchanges can tell you what a resource is.
>> There are several reasons for this.
>>  1. The absence of a GET/200 giving W(T,R) does not mean that W(T,R)
>>    isn't true.
>>  2. Two Things T,T' could have W(T,R) but not W(T',R) for some
>>    REST-representation R not hitherto obtained by a GET/200 exchange.
>>  3. T and T' could agree on the truth or falsehood of *every*
>>    W-statement and *still* be different
>
> What does this mean? A Thing has an opinion about truth of statements??
>
>>
>> Information distinguishing such Things, if it were available, would
>> have to come through a different channel (e.g. RDF).
>>
>> httpRange-14
>> ------------
>>
>> Let IR be a proper subclass of Thing containing the domain of W,
>> i.e. suppose W(T,R) implies that T is in IR.
>>
>> Properties of IR:
>>  Grandfathering: "web resources" (those for which we get 200s) are in IR
>>    - this is a consequence of the above stipulation.
>
> Only if their URIs (the ones that deliver the 200's) refer to something.
> They might not.
>
> Perhaps you mean, those referred to by a URI from which we get a 200. In
> which case, OK, yes.
>
>>  TimBL: "generic resources" are in IR (genont)
>>  TimBL: literary works are in IR  (Pat Hayes disagrees)
>>
>>  TimBL: dogs and people are disjoint with IR
>>    (by extension: anything physical)
>>  TimBL: strings and numbers are disjoint with IR
>>    (by extension: anything mathematical)
>>  TimBL: REST-representation is disjoint with IR
>>    (JAR doesn't see the point)
>>  Pat: RDF graphs are not in IR
>
> Follows from Tim's no-math criterion above. RDF graphs are (normatively
> defined to be) sets.
>
>>
>>  TimBL: members of IR are not determined by their W-relations
>>    i.e. one might have W(T,R) = W(T',R) for all REST-representations
>>    R, yet T != T'   [time sheet example]
>
> Sad, if true.
>
> Pat
>
>>
>> We have three theories of IR in the works now: Dan's speaks-for
>> theory, Alan's what-is-on-the-web theory, and JAR's property-transfer
>> theory.
>>
>>
>
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Received on Monday, 24 May 2010 13:04:41 UTC