- From: Dan Brickley <danbri@google.com>
- Date: Sat, 22 Feb 2014 03:11:36 +0000
- To: W3C Web Schemas Task Force <public-vocabs@w3.org>
- Cc: Denny Vrandečić <vrandecic@google.com>
Here's another example along the lines I sketched recently, after sitting down with Denny today and looking at Wikidata. It is an attempt to show how "types" handled externally from schema.org could be written (in this case in RDFa) alongside basic schema.org types. We revisit the use case of having more kinds of "place of workship" than are anticipated in the schema.org core. A couple of things to note about Wikidata first: 1. it does have basic properties for 'instance of' and 'subclass' but there is no formal or software-backed understanding of these. Most of Wikidata views these as simply more data about an entity. The Wikidata software does not really have a notion of entities having types, this is something added at a later level as data. Perhaps if type-like constructs become common and popular in the community some UI or API support might emerge (by very rough analogy, think about hashtags and retweets in Twitter, which initially were also "just in the data"). I'll try to write type-like-entity instead of 'type' when talking about Wikidata. 2. although the factual data in Wikidata is currently often fairly thin, there are already many mappings to other identifiers, e.g. 1-2 million have Freebase links, which in turns brings in more factual background data. So here's an example, we describe the entity https://www.wikidata.org/entity/Q2046262 (Pagoda Songyue) as falling into the wikidata type-like-entity https://www.wikidata.org/entity/Q199451 (Pagoda), and then anchor that in the schema.org 'PlaceOfWorship' type. <div vocab="http://schema.org/" typeof="PlaceOfWorship https://www.wikidata.org/entity/Q199451"> <span property="name">Pagoda Songyue</span> <span property="description">One of the few intact sixth-century pagodas in China, located at the Songyue Monastery on Mount Song.</span> <link property="url" href="https://www.wikidata.org/entity/Q2046262" /> <link property="sameAs" href="https://en.wikipedia.org/wiki/Songyue_Pagoda" /> <link property="sameAs" href="http://www.freebase.com/m/03bz2xf" /> <div itemprop="geo" itemscope itemtype="http://schema.org/GeoCoordinates"> <meta itemprop="latitude" content="34.501611" /> <meta itemprop="longitude" content="113.015917" /> </div> </div> a) https://www.wikidata.org/entity/Q199451 is the type-like-entity, "Pagoda" in Wikidata b) https://www.wikidata.org/wiki/Property:P279 is the subClassOf relation, ("all of these items are instances of those items; this item is a class of that item"). c) https://www.wikidata.org/wiki/Q1370598 is "Place of Worship" in Wikidata. This type-like-entity has associations with 'architectural structure' and 'religion' within Wikidata. This would be the natural place also to express a link to 'http://schema.org/PlaceOfWorship', but that statement hasn't yet been expressed, and there might be some details to work out on the mechanics. d) https://www.wikidata.org/wiki/Property:P31 is the instanceOf relation in Wikidata; ("this item is a concrete object (instance) of this class, category or object group"). Last time I posted something in this direction (funeral homes, http://lists.w3.org/Archives/Public/public-vocabs/2014Feb/0007.html) there was a concern (Aaron's, in http://lists.w3.org/Archives/Public/public-vocabs/2014Feb/0010.html ) that schema.org search engines might not care about other namespaces so much. I'd like to explicitly set that aside for now, along with the concern the lack of UI for these types. It's reasonable to ask questions about both, but for now I'd like to concentrate on making sure the representational machinery matches up. >From looking at this today, it seems already possible to create descriptions that draw on "types" from Wikidata alongside matching broader types from schema.org. It seems possible within Wikidata to talk about an entity being an "instance of" a type that shows up as another entity within Wikidata, and for that type entity to have subClass links to broader wikidata types. The Wikidata machinery (and hopefully community process!) should also make it fairly easy to add properties linking these type-like entities to other types such as at schema.org, so that the wider community can keep collective notes on the relationships between the type-like entitites Q1370598 and Q199451 in Wikidata and schema.org's 'PlaceOfWorship' type. In http://blog.schema.org/2012/05/schemaorg-markup-for-external-lists.html a while back from schema.org, we wrote about the importance of 'external enumerations'. Wikidata barely existed back then. Now that Wikidata is real, I'd like to encourage people to take a look. The potential for combining Wikidata and schema.org is well worth some thought... Topic for another day: what do we do about enumerations where instantiation-oriented type hierarchies are not a great fit? There are various properties in schema.org where we want to be more structured than saying "values are a string or url", but where schema.org as a project doesn't directly want to draw up a list of all the possible values. For example restaurant/menu cuisines (e.g. http://schema.org/servesCuisine http://schema.org/recipeCuisine) . Let's come back to that one in the context of MiniSKOS. Wikidata may have a role to play there too. cheers, Dan ps. for more background on Wikidata, see Denny's recent article at http://www.computer.org/portal/web/computingnow/content?g=53319&type=article&urlTitle=the-rise-of-wikidata
Received on Saturday, 22 February 2014 03:12:04 UTC