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“no difference between a URI that dereferences to an RDF graph and a URI that dereferences to some other digital content or to a URI that doesn't derefence to anything.”

 

Karen – you can make any sort of RDF statement you like:

<http://subjectURI>  predicate  <http://ObjectURI>

And if http://ObjectURI  dereferences only to an  HTML representation --  or if there is no representation at all – nobody can stop you from making that RDF statement.    We’re talking about good linked data practice.  A linked data link should yield RDF, that’s the essence of linked data, if it doesn’t what is the advantage of representing it as a link rather than a literal?

 

Ray

 

From: Bibliographic Framework Transition Initiative Forum [mailto:[log in to unmask]] On Behalf Of Karen Coyle
Sent: Tuesday, November 17, 2015 8:48 AM
To: [log in to unmask]
Subject: Re: [BIBFRAME] Properties of Item proposal

 

 

On 11/16/15 1:14 PM, Denenberg, Ray wrote:

Karen,  take this one step at a time.  Suppose I have a triple:

 

     <some subject>   bf:someProperty   <http://someURI>

 

Where again I am using turtle notation and I am explicitly enclosing   http://someURI  in angle braces.   I claim that http://someURI (enclosed in angle braces) must be dereferenceable as RDF (meaning that there is an RDF representation of that resource, http://someURI, which may be one of many representations, and I can get that RDF representation by doing a get on it requesting RDF via content negotiation).

 

Do you not agree?


No, there is no difference between a URI that dereferences to an RDF graph and a URI that dereferences to some other digital content or to a URI that doesn't derefence to anything.


 

 

(And you’re saying that “RDF resource” is defined in the documents you cited, but that expression doesn’t even occur in any of those documents.  Nowhere. So I’m confused.)


Those documents define what "resource" means in the context of RDF. I don't see how "RDF resource" can be anything but a resource as defined in the context of RDF. If "RDF resource" is being used with a different meaning, then it is a misnomer. I suspect that for most people it means "a thing, not a string." But that is different to what you are saying.

kc


 

 

 

Ray

 

From: Bibliographic Framework Transition Initiative Forum [mailto:[log in to unmask]] On Behalf Of Karen Coyle
Sent: Monday, November 16, 2015 3:44 PM
To: [log in to unmask]
Subject: Re: [BIBFRAME] Properties of Item proposal

 

 

On 11/16/15 10:37 AM, Denenberg, Ray wrote:

Hi Karen – Yes there certainly is a terminology issue, particularly because the expression “RDF resource” does not have a formal definition, anywhere (that I have ever been able to find).


Actually, Ray, the quotes I gave you in my email are indeed the formal definition from the W3C specifications. There is probably an even more formal definition somewhere using virtually unreadable notation, but I think that what the human-readable documents say is quite clear -- which is that a resource is "anything that an RDF graph describes" and that it can be either an IRI or a literal. I agree with you that folks often refer to IRIs as resources as opposed to literals, but that's a misnomer. Another way of saying this is "string vs. thing" but there's probably some ambiguity in that as well. But most importantly, as I said below, nowhere have I encountered any statements that there is any distinction made that what one obtains upon dereferencing must be "RDF". In fact, I don't know what that actually means.

Your http://hdl.loc.gov/loc.pnp/cph.3g11323, which very clearly follows the rules for an IRI (and IRIs do not need to be dereferenceable) is an IRI. What it does or does not dereference to does not change that. You can treat an IRI as a literal string (I don't think there's anything in RDF to prevent that) -- and therefore indicate that you don't intend it to be actionable as an IRI. However, again, your distinction of "imply that you can retrieve RDF by dereferencing" is not familiar to me.

kc




However, whenever I encounter the expression it seems to be used in the sense that I’m using it.   Which is this:

In any RDF triple the object is a literal or an RDF resource.  A literal is of course a resource; and I am making a distinction between “resource” and “RDF resource”. 

So, the object of a triple is either:

1.       a literal, in which case it’s enclosed in quotes (assuming turtle serialization); or   

2.       not enclosed in quotes, in which case it is an RDF resource URI (either enclosed by curly braces or using namespace prefix notation), or a blank node id.   

 

For case 2, the URI can be dereferenced resulting in an RDF description or if it is a blank node it points to an RDF description.


Do you agree (so far)?  If you think I’m using the expression “RDF resource” incorrectly then what is your definition?  If you think “RDF resource” and “resource” mean the same thing, I disagree, but then, I could be wrong, since “RDF resource” has no formal definition.  But I’m using it in the sense that I see it used.

 

Anyway, having said all that, getting back to the example at hand

 

      bf:electronicLocator  [

                 a    bf:ElectronicLocator ;

                  rdf:value   “http://hdl.loc.gov/loc.pnp/cph.3g11323” ] ;

 

I maintain that it would be incorrect to instead say:

 

bf:electronicLocator  <http://hdl.loc.gov/loc.pnp/cph.3g11323” >

 

because that would imply that you can retrieve RDF by dereferencing http://hdl.loc.gov/loc.pnp/cph.3g11323 , which (as far as I know) you can’t.

 

Ray

 

 

From: Bibliographic Framework Transition Initiative Forum [mailto:[log in to unmask]] On Behalf Of Karen Coyle
Sent: Sunday, November 15, 2015 8:30 PM
To: [log in to unmask]
Subject: Re: [BIBFRAME] Properties of Item proposal

 

 

On 11/12/15 12:05 PM, Denenberg, Ray wrote:

Hi Joseph – thanks for the comments and questions.  I want to address two points, while we are still discussing the other suggestions.

 

bf:electronicLocator is, at present, conceived to be a datatype property; its expected value is a literal.  We could change that to an object property if that’s what people want, however, the URI would still be a literal, because it is not an RDF resource.   In the example, the electronic locator is http://hdl.loc.gov/loc.pnp/cph.3g11323 and this is not an RDF resource. (By RDF resource, we mean, you can dereference the URI and get RDF in response. You can’t for this URI.)


Ray, can you say more about this concept of a non-resource? AFAIK, many URIs do not dereference to  "RDF in response", but they are still considered resources in RDF. I'm looking at:

"90. Resource
In an RDF context, a resource can be anything that an RDF graph describes. A resource can be addressed by a Unified Resource Identifier (URI)." [1]

"Any IRI or literal denotes something in the world (the "universe of discourse"). These things are called resources. Anything can be a resource, including physical things, documents, abstract concepts, numbers and strings; the term is synonymous with "entity" as it is used in the RDF Semantics specification [RDF11-MT]."[2]

There is similar language in the RDF 1.1 primer. [3]

This might be a terminology issue, but even accepting a different terminology, I'm not aware of any distinction where a response to the dereferencing of an IRI must be RDF (meaning? ntriples? JSON-LD?) rather than any RDF:resource (e.g. a jpeg file, an html file, an avi file).

kc
[1] http://www.w3.org/TR/2013/NOTE-ld-glossary-20130627/#resource
[2] http://www.w3.org/TR/rdf11-concepts/#resources-and-statements
[3] http://www.w3.org/TR/rdf11-primer/




If bf:electronicLocator were to be redefined as an object property, then instead of this:

 

<http://bibframe.example.org/item/item5>      

          a                                        bf:Item ;

          bf:electronicLocator      “http://hdl.loc.gov/loc.pnp/cph.3g11323”  ;

……

 

It might look like this:

 

<http://bibframe.example.org/item/item5>      

          a                                        bf:Item ;

          bf:electronicLocator  [

                                                   a    bf:ElectronicLocator ;

                                                    rdf:value   “http://hdl.loc.gov/loc.pnp/cph.3g11323” ] ;

      ……

 

Where here we now have defined class bf:ElectronicLocator, but the URI is still a literal.

 

 

Second, should bf:itemOf (property of item) have a reciprocal property, bf:hasItem (property of Instance).

I don’t know; opinions are welcomed on this question.  We did not include it in the draft for this reason: an item knows (or should know) what Instance it is an Item of.  An Instance in general does not know the existence of all items that claim to be an item of that Instance. So if there were to be a property bf:hasItem, it could be used within an Instance to point to all items that that Instance knows about with the disclaimer that it doesn’t claim to point to all its items. If, as such, this would be useful then we can add the property.  (The same dilemma applies to instanceOf and hasInstance. And granted, these are both included in BIBFRAME 1.0.)

 

Ray

 

 

From: Bibliographic Framework Transition Initiative Forum [mailto:[log in to unmask]] On Behalf Of Joseph Kiegel
Sent: Tuesday, November 10, 2015 1:39 PM
To: [log in to unmask]
Subject: [BIBFRAME] Properties of Item proposal

 

Items in BIBFRAME may serve different purposes, which is not addressed in the Items proposal.  A relatively narrow purpose is to support the user task obtain, while a more complex one is to support a working circulation system.  The properties elaborated in the proposal are not sufficient even for the user task obtain.  Here are comments on them.

 

bf:electronicLocator:  should the expected value be a URI?  It seems odd to express URLs as literals in linked data.

 

 

bf:heldBy and bf:subLocation:  the MARC holdings format and many library systems recognize three levels of location information: organization, library and sublocation within a library.  BIBFRAME should support the same number of levels:  for example, it should add a property such as bf:location, which is intermediate between bf:heldBy and bf:subLocation. 

 

bf:heldBy University of Washington Libraries

bf:location:  Art Library

bf:subLocation:  Reference stacks

 

bf:heldBy University of Washington Libraries

bf:location:  Engineering Library

bf:subLocation:  Reference stacks

 

Without bf:location, reference or general stacks locations in different buildings appear to be the same.

 

 

bf:itemOf:   is a reciprocal property needed?  For example, bf:hasItem, a property of bf:Instance with an expected value of bf:Item.

 

 

Two properties are lacking from the proposal:  bf:itemStatus and bf:circulationCharacteristic

 

bf:itemStatus:  it is crucial to inform users of the status of an item, e.g. available, checked out, missing, withdrawn, at the bindery, etc.

 

bf:circulationCharacteristic:  another important aspect of materials is the general policy that governs them, e.g. circulating or library use only.  It is tempting to try to include this characteristic in bf:itemStatus, but they are independent aspects.  LUO materials may be missing, at the bindery or even checked out (e.g. faculty loans of reference materials). 

 

 





-- 
Karen Coyle
[log in to unmask] http://kcoyle.net
m: +1-510-435-8234
skype: kcoylenet/+1-510-984-3600




-- 
Karen Coyle
[log in to unmask] http://kcoyle.net
m: +1-510-435-8234
skype: kcoylenet/+1-510-984-3600



-- 
Karen Coyle
[log in to unmask] http://kcoyle.net
m: +1-510-435-8234
skype: kcoylenet/+1-510-984-3600