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Subject: RE: [xdi] RE: The use-mention distinction
Bill, see [=Drummond] inline. From: Barnhill,
William [USA] [mailto:barnhill_william@bah.com] Tossing out a few thoughts... Am I correct that =Drummond/$has/+friend means the instance
=Drummond of the class of individuals (impl. by =) has at least one property
value of the property +friend? [=Drummond] The proposed semantics of the XDI
$has predicate is aggregation between resources, i.e., =drummond/$has/+friend
simply means the resource =drummond aggregates the resource +friend in its own
context. It doesn’t by itself imply anything about property values of
=drummond or =drummond+friend. Those would be implied by XDI RDF statements
like =drummond/$is$a/+person and +friend/$is$a/+person. Also, am I correct that =Drummond/+friend is not a statement? For my
purposes I would treat this as a query pointing to the results of the form
=Drummond/+friend/XXX. [=Drummond] Agreed. I think the implied XDI
RDF statement is =drummond/+friend/ (i.e., the RDF object is a b-node), but I
could be wrong about that. If =Drummond/$has/+friend is the same as =Drummond/+friend, then
=Drummond/+friend/=Bill.Barnhill is the same as what? Would this be =Drummond/$has/+friend//$is/=Bill.Barnhill?
If so, how do I know that $is shouldn't be a $has? [=Drummond] =drummond/$has/+friend is NOT
the same as =drummond/+friend/. The first is an assertion of an aggregation
relationship between =drummond and +friend. The second is a +friend
relationship between =drummond and an unknown set of other XDI subjects. =Drummond From: Chasen,
Les I may be dense here
but I just don’t see how the requirement “XDI RDF statements, which are all represented by XRIs, MUST NOT
need to be changed in order to be combined into other XDI RDF
statements” means that we need to allow GCS delimited XRIs. Another thing that confuses me is
that you are transforming =Drummond/$has/+friend into =Drummond+friend.
Why not leave it =Drummond/$has/+friend? Similarly why
doesn’t the transformation from =Drummond/$has/+friend to =Drummond*(+friend)
work? I am free at 5 (EST). Wanna call me? From: Drummond Reed
[mailto:drummond.reed@cordance.net] Les, the requirement coming from the XDI
TC for the GCS Delimiter proposal is very concrete and specific. It’s the
first one listed on the proposal page, i.e.:
http://wiki.oasis-open.org/xri/XriThree/GcsDelimiter#head-4d6c59f23b76cda5ab39226f6c6158f87716be22 In one sentence, the requirement is that
XDI RDF statements, which are all represented by XRIs, MUST NOT need to be
changed in order to be combined into other XDI RDF statements. For example
under current XRI 2.0 syntax the XDI RDF statement =drummond/$has/+friend
CANNOT be expressed as the XRI =drummond+friend, because +friend cannot be used
directly in the context of =drummond. The GCS Delimiter proposal fixes that. I’ll call you tomorrow to discuss
via voice. =Drummond From: Chasen, Les
[mailto:les.chasen@neustar.biz] OK, Drummond, my hat
is off to you. You sure have pulled some interesting references to back
up this proposal. I had never heard of the use_mention_distinction
before. How many English speaking humans do you think have? Random thoughts
…. This still does not
tell me why XDI or XRI needs this capability. I am still looking for the
requirement. All of these arguments seem to be justifying the
proposed solution. Using the English
language as a model is scary in its complexity. Nuances such as these
often get us in trouble. Rather than
precision this seems to bring ambiguity especially since there are no proposed
policies on how they are used. If looking for precision it would seem
looking at mathematical syntax rather than linguistic syntax may be a better
guide. Seems to me that if
there “really” needs to be a distinction between “use”
and “mention” it should be done in the XRD. (Note:
first set of quotes intended to be scary quotes while the second set intended
to be mentions or is it uses … I don’t know … I confuse
myself) Is the requirement
to enable use_mention or the previously mentioned need of
scary_quotes? I am not certain but I think these are different
concepts. I wonder, should XRI and XDI support both
use_mention and scary_quotes. How about italics and object language and
formal language and kleene stars and the million other language constructs that
can be found in Wikipedia. I am not a linguist and do not claim to
understand these concepts. I still have to ask
why this is needed. The only argument that makes any sense to my simple mind
is cosmetics when stringing large XRIs together in statements such as $IS$A or
$HAS$A or +international+employment$contract$sig$d. From: Drummond Reed
[mailto:drummond.reed@cordance.net] > Les wrote: > > What is the english difference
between these two statements: > With the caveat that English equivalents
of XDI RDF statements are only an analogy, here’s the translation
(assuming $sig = “signature” and $d = “date”):
XRI
+international+employment$contract$sig$d
English
international employment contract signature date
XRI
+international*(+employment)*($contract)*($sig)*($d)
English
international “employment” “contract”
“signature” “date” The key point being that an XRI
cross-reference expresses roughly the same concept as the English concept of
the Use-Mention Distinction:
http://en.wikipedia.org/wiki/Use_mention_distinction As explained in the introduction to that
Wikipedia page: The use–mention distinction (sometimes
referred to as the words-as-words distinction)
is the distinction between using
a word (or phrase) and mentioning
it. For example, the following two sentences illustrate use and mention of the
word cheese:
The first
sentence is a statement about the substance cheese. It uses the word cheese to describe its referent. The second is a statement
about the word cheese.
It mentions the word without
using it. In
written language, mentioned words or phrases often appear between quotation marks ("Chicago" contains three
vowels) or in italics (When I refer to honey,
I mean the sweet stuff that bees make), and some authorities insist that
mentioned words or phrases must always be made visually distinct in this
manner. Used words or phrases (much more common than mentioned ones) do not
bear any typographic distinction. ************** The irony behind the http://wiki.oasis-open.org/xri/XriThree/GcsDelimiter
proposal is highlighted by the last sentence above where it says, “Used
words or phrases (_much more common_ than mentioned ones)…”
(emphasis added). Our history in XRI is that first we
recognized, way back in the prehistory days (2000) that XRI syntax needed a way
to encapsulated (and thereby reuse) identifiers from other contexts (most
specifically, absolute URIs, but also relative URIs and other string-based
identifiers). We invented the parenthetical cross-reference syntax to do that.
Since that was the ONLY mechanism we had for reusing identifiers, we also used
it to reuse global XRIs in the context of other global XRIs. That meant that
the ONLY way to refer to =drummond in the context of @cordance was to express
it as either:
@cordance*(=drummond)
@cordance!(=drummond) Therefore, to use the terminology of the
Wikipedia articile, we semantically interpreted such a cross-reference as a _use_ of =drummond and not a _mention_ of =drummond. However as we began to run into issues
with restricting global XRI reuse to cross-reference syntax, the idea first
arose that GCS characters could function as delimiters just like LCS characters
(* and !). That meant we could express one global XRI directly in the context
of another global XRI, e.g.:
@cordance=drummond This syntax was directly parallel to
English, where the direct _use_
of one English word in the context of another English word requires no special
syntax other than creating an ordered set of the words. This is expressed in
the last sentence of the Wikipedia quote above: Used words or phrases (much more common than mentioned ones) do not
bear any typographic distinction. From an XRI standpoint, suddenly
everything snapped into place. The ordinary _use_
of one global XRI in the context of another XRI could be accomplished simply by
creating an ordered set of the global XRIs, without any special syntax. This
would align it directly with English. Then the special exception, i.e, the _mention_ of a global XRI without intending
its normal use, would be represented by cross-reference syntax. That means in
English:
XRI
@cordance=drummond
English
Cordance Drummond
XRI
@cordance*(=drummond)
English
Cordance “Drummond” Following the use-mention distinction, the
presumption would be that the =drummond in @cordance=drummond is the regular _use_ of =drummond, and therefore is a
reference – in Cordance’s context – to the same entity
referred to by =drummond in its own (global) context. By contrast, the presumption would be that
the =drummond in @cordance*(=drummond) is a _mention_
of =drummond, and therefore should NOT be interpreted as a reference to
=drummond in ordinary _use_.
(What it should be a reference to is up to @cordance as the authority for this
subsegment.) Personally, I think it is a combination
of: A) the evolutionary history of XRI, and B) the subtlety of the use-mention
distinction, that has take us so long to recognize and understand this issue,
which is why I don’t blame Les for really pressing us to explain it. =Drummond |
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