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Facets was Re: CreativeWork can't be a Product?

From: Karen Coyle <kcoyle@kcoyle.net>
Date: Tue, 08 Oct 2013 07:34:24 -0700
Message-ID: <525417F0.1000301@kcoyle.net>
To: public-vocabs@w3.org
Guha, thanks for confirming the way I was reading the schema.

As DanBri has heard me say, there is some irony in the tendency of 
Semantic Web development to lean heavily on hierarchy when its goal is 
to create a graph. Hierarchies, as we see here, are traps that we humans 
too easily fall into. It is obvious to me that if our data is to be a 
graph, our vocabularies also need to be graph-like, not hierarchical.

Any "thing" can be offered. Any "thing" can have a location, exist in 
time, be acted on. Some combinations may not make sense (you don't 
manufacture cats and you don't take the appendix out of a stone), but 
it's probably better to allow volcanoes to have fax machines than try to 
define everything "correctly." Usage will win out in the end.

I have mentioned before the concept of facets.[1] The pre-computing idea 
of facets was fairly restrictive due to physical restrictions,[2] but 
today we could have more freedom. Offer could stand alone, as could 
geographical location, as could some concept of "operating as a business 
or service" that includes street addresses. Hours of availability could 
apply to professors as well as stores and government offices and TV shows.

There could still be some restrictions, so as not to go too far beyond 
what "normal people" think about the data they are marking up and to 
provide guidance. You could limit creators to CreativeWork and 
manufacturers to Product. (This seems to be the subtext behind those two 

I see this as being inherently practical, not theoretical. What 
combinations do we think we need? In the development of schema, someone 
saw that Product needed offer, but didn't realize that other things 
might need offer as well. Offer has proven itself to be of general use 
and could be given the status of a facet that can be used wherever 
needed. It would no longer be subordinate to Product, but would stand 
alone (sub to Thing). In terms of how it would be used, there are 
choices: it could either be declared a super-type to particular types, 
or could be declared in instance data as an additional type, or could be 
considered to be available to instance data without an explicit 
declaration, as inherent in the use of any schema.org type.


[1] https://en.wikipedia.org/wiki/Faceted_classification
[1] https://en.wikipedia.org/wiki/Colon_classification

On 10/7/13 8:54 PM, Guha wrote:
> Absolutely. The assumption is that if an entity is an instance of
> multiple types, this should be stated explicitly (as opposed to using a
> property from a different type and expecting a reasoner to infer the type).
> Guha
> On Mon, Oct 7, 2013 at 7:01 PM, Karen Coyle <kcoyle@kcoyle.net
> <mailto:kcoyle@kcoyle.net>> wrote:
>     Something else that has made it hard for me to generalize from the
>     use of product ontology to the use of additional schema.org
>     <http://schema.org> types is that the product ontology use provides
>     an additional type but no additional properties. It feels kind of
>     like an aside. The schema.org <http://schema.org> use case seems to
>     provide different capabilities, and has a more substantial impact on
>     the instance metadata.
>     Admittedly, there was the quote that flew through here today saying
>     that proper reasoners would infer from the properties that one was
>     making a statement about additional types, but it does not seem that
>     that assumption has been in force during most of the development of
>     schema.org <http://schema.org> -- instead, multiple typing within
>     schema.org <http://schema.org> has been done explicitly in the
>     design of classes and properties rather than being relegated to
>     instances and reasoners.
>     kc
>     On 10/7/13 5:20 PM, Aaron Bradley wrote:
>         The documentation here leaves a lot to be desired.  I think, at
>         the very
>         least, an example of this in use on schema.org
>         <http://schema.org> <http://schema.org> with
>         a schema.org <http://schema.org> <http://schema.org> URL would
>         be useful.  As far as I know
>         ProductModel [1] is the only type that uses additionalType in
>         example
>         code, and this very much in keeping with what the property's
>         description
>         describes as the "typical"  use for the property in "adding more
>         specific types from external vocabularies in microdata syntax."
>         Is <link> required to employ additionalType?  Once an
>         additionalType is
>         declared, can properties be associated with it *and* the
>         initially-declared item?  There's no guidance on this or any other
>         information on schema.org <http://schema.org>
>         <http://schema.org> about implementing
>         additionalType.
>         Note that additionalType proposal [2] included "Changes to
>         http://schema.org/docs/__datamodel.html
>         <http://schema.org/docs/datamodel.html>" - namely the insertion of a
>         section "Handling of Multiple Types."  That section obviously
>         never made
>         its way to the Data Model page.
>         [1] http://schema.org/ProductModel
>         [2] http://www.w3.org/wiki/__WebSchemas/__additionalTypeProposal
>         <http://www.w3.org/wiki/WebSchemas/additionalTypeProposal>
>         On Mon, Oct 7, 2013 at 4:59 PM, Guha <guha@google.com
>         <mailto:guha@google.com>
>         <mailto:guha@google.com <mailto:guha@google.com>>> wrote:
>              This is what http://schema.org/__additionalType
>         <http://schema.org/additionalType> is for.
>              All of an object's types have the same standing.
>              guha
>              On Mon, Oct 7, 2013 at 3:19 PM, Wes Turner
>         <wes.turner@gmail.com <mailto:wes.turner@gmail.com>
>              <mailto:wes.turner@gmail.com
>         <mailto:wes.turner@gmail.com>>> wrote:
>                  Is this what http://schema.org/__additionalType
>         <http://schema.org/additionalType> is for?
>                  --
>                  Wes Turner
>                  On Mon, Oct 7, 2013 at 3:46 PM, Aaron Bradley
>                  <aaranged@gmail.com <mailto:aaranged@gmail.com>
>         <mailto:aaranged@gmail.com <mailto:aaranged@gmail.com>>> wrote:
>                      Dan's solution and Martin's link are excellent
>         ones.  Just a
>                      quick FYI a previous discussion and a proposal
>         related to it
>                      provide some further information on this type of
>         conundrum
>                      in schema.org <http://schema.org> <http://schema.org>:
>         http://lists.w3.org/Archives/__Public/public-schemabibex/__2013Jan/0182.html
>         <http://lists.w3.org/Archives/Public/public-schemabibex/2013Jan/0182.html>
>         http://www.w3.org/wiki/__WebSchemas/__SchemaDotOrgMetaSchema
>         <http://www.w3.org/wiki/WebSchemas/SchemaDotOrgMetaSchema>
>                      A fragment from the former reference:
>                      > Assuming they take OWL seriously, they would
>         infer new types for the
>                      > entity if properties were mixed and matched. If
>         example, if the claimed
>                      > type is schema:Book and somebody used the
>         schema:sku property, they
>                      > could infer it is also a schema:Product.
>                      On Mon, Oct 7, 2013 at 1:37 PM, Dan Scott
>                      <dan@coffeecode.net <mailto:dan@coffeecode.net>
>         <mailto:dan@coffeecode.net <mailto:dan@coffeecode.net>>> wrote:
>                          On Mon, Oct 07, 2013 at 09:16:01PM +0100,
>         Chilly Bang wrote:
>                              Hello!
>                              i'm busy at the moment with marking up with
>                              microdata of an online bookstore and
>         realized the
>                              following dilemma:
>                              if a page is about describing and selling of a
>                              CreativeWork/Book, so i come to selling
>         properties
>                              with itemprop="offers" itemscope=""
>                              itemtype="http://schema.org/____Offer
>         <http://schema.org/__Offer>
>                              <http://schema.org/Offer>". But on this way
>         i can't
>                              describe the book i sell like Product, with
>                              product's properties - i can't find any
>         passage from
>                              CreativeWork to Product. There is in fact a
>         passage
>                              from Offer to Product, with
>         itemprop="itemOffered"
>                              itemscope=""
>         itemtype="http://schema.org/____Product
>         <http://schema.org/__Product>
>                              <http://schema.org/Product>", but repeating
>         isn't a
>                              good way, beside of this it isn't easy to
>         get such
>                              passage into html, even with itemref.
>                              I see no possibility to go the way
>                              CreativeWork->Product->Offer (or
>                              CreativeWork->Product and
>         CreativeWork->Offer), but
>                              only CreativeWork->Offer, or Product->Offer.
>                              CreativeWork can't be a Product or am i wrong?
>                              Imho CreativeWork surely can own product's
>                              properties so it must gladly have a passage
>         from any
>                              CreativeWork property to Product.
>                          You can just use both types in the itemtype
>         declaration,
>                          for example,
>                          itemtype="Book Product".
>                          We're doing this in the #schemabibex group to
>         express
>                          offers for a given
>                          item. And Martin gave a wonderful example of this
>                          approach on this list
>                          just a few days back at
>         http://lists.w3.org/Archives/____Public/public-vocabs/2013Sep/____0206.html
>         <http://lists.w3.org/Archives/__Public/public-vocabs/2013Sep/__0206.html>
>         <http://lists.w3.org/Archives/__Public/public-vocabs/2013Sep/__0206.html
>         <http://lists.w3.org/Archives/Public/public-vocabs/2013Sep/0206.html>>
>     --
>     Karen Coyle
>     kcoyle@kcoyle.net <mailto:kcoyle@kcoyle.net> http://kcoyle.net
>     m: 1-510-435-8234 <tel:1-510-435-8234>
>     skype: kcoylenet

Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet
Received on Tuesday, 8 October 2013 14:34:56 UTC

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