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Re: schema.org as reconstructed from the human-readable information at schema.org

From: Guha <guha@google.com>
Date: Thu, 24 Oct 2013 18:31:12 -0700
Message-ID: <CAPAGhv9jyTHedoR8pxmri0nrN1tEWifQVqReEnEJg39LF4ZMiw@mail.gmail.com>
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
Cc: W3C Vocabularies <public-vocabs@w3.org>
Mostly right. See below for corrections. What is the purpose of this
'reconstruction', if I may ask?


On Thu, Oct 24, 2013 at 6:13 PM, Peter F. Patel-Schneider <
> wrote:

> I read over the human-readable web pages at schema.org (except for some
> of the type and property pages there) and came up with the following
> reconstruction of what schema.org is, ignoring anything to do with the
> surface syntaxes of schema.org.
> Comments are welcome, particularly comments that include evidence that
> particular parts of the reconstruction below do not correspond to
> human-readable information available at schema.org or that there is
> significant human-readable information available at schema.org that is
> not reflected here.
> Peter F. Patel-Schneider
> Nuance Communications
> Types
>   There is a collection of types, with two roots, http://schema.org/Thing
>   and http://schema.org/Datatype, organized in a multi-parent
>   (generalization) taxonomy.
>   Each type is a URL under http://schema.org/.

The type is not a URL. It is referred to by a URL.

>   All the types directly under http://schema.org are specified in
> schema.org

Not sure what this means.

>   Some types are enumeration types, (whose elements are one of a set of
> URLs?).

See earlier comment.

>   Some types are datatypes.
>   Each type has a collection of allowable properties.
>   Subtypes of types can be created by appending /... to a type URL.
> Datatypes
>   There are the following datatypes with appropriate data values
>     Boolean, Date, DateTime, Number (Float, Integer), Text (URL), Time
> Properties
>   There is a collection of properties, organized in a (single-parent?)
>   taxonomy with multiple roots.

There is no organizaton of properties.

>   Each property is a string.

Properties are first class entities. Unlike some systems (like description
logics), schema.org does not make a hard distinction between individuals,
types and properties. They are all items/objects/entities.

>   Properties can have any number of ranges each of which are types.
>   Each value for the property in an item should have one of the range types
>   (for the property itself, not including the range types of any parent)
>   as (an ancestor of) (one of?) its types (or otherwise belong to the
> type).

I am having difficulty parsing this sentence.

>   Properties are not restricted to starting with the properties specified
> in
>   schema.org

Don't understand what this means.

>   Subproperties can be created by appending /... to a property.
> Items

See earlier comment about schema.org being in the spirit of rdf, cycl, etc.
and not making a hard distinction between items and types.

>   Items are things in the world, including information things
>   Items can have a type (or types?)

Everything in schema.org can have multiple types

>   Items can have one or more property-value pairs, where
>     the property is an allowable property for the type (one of the types?)
>     of the item or one of its ancestors
>     and the value is either a data value, a piece of text, or an item
>   Some items are described by a web page at a particular URL (URL
> property)

  Some items can be identified by a URL (sameAs property)
>   Some items have names, images, descriptions, and additionalTypes

additionalTypes is just a microdata specific vocabulary extension to allow
multiple types.

Received on Friday, 25 October 2013 01:31:40 UTC

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