See below for comments - thanks, John
-----Original Message-----
From: Yaron Koren []
Sent: Thursday, March 04, 2010 4:59 PM
To: John McClure
Cc: David Raison; semediawiki-devel
Subject: Re: [SMW-devel] Recurring Events: "Every first saturday of a month"

This is interesting, though it seems irrelevant to this discussion, which is about storing data, not querying it... unless I'm missing something.


On Thu, Mar 4, 2010 at 5:32 PM, John McClure <> wrote:
>Does anyone else have a suggestion? :)

Normalization would show the day of a week is an attribute of a date. So:
* An #ask should be able to say ?Date.Weekday
* IOW, a "Date" is a first class object as much as, say, a "Place" is
* IOW, I'd like to see SMW standardize "category:Dates" and its properties
* And I'd like to see the ability to set those properties from a 'container'
object's template but see below my idea for an #about function
* IMHO, {{#set: page-or-sio-name|propname=value}} would resolve alot of n-ary
issues but see below discussion for the #about function

I worked backwards to address the storage process & protocol, starting from the query that I'd rather see. The query is one that uses the 'dot' operator to traverse object nodes & then terminating at a text-node, rather than simply having an unnormalized 'camel case' text-node propery name (such as the proposed monstrosity) which is lame from the view that, because it is unnormalized, then by definition it is not reusable in other contexts.
Obviously noone wants to require a page for every date. Rather, queriable built-in Date objects can be simulated &or retrieved by SMW either from SIOs or MV properties associated with the [[:category:Dates]] page OR from pages in the wiki so categorized.
SIOs seem a better candidate because they are queriable, though MV properties suggest better performance. If SIO was used, then each 'date' object would be linked to the :Category:Dates page via a "Category" property for the date object. If MVPs are used, then each 'date' object would be referenced by say an "Instances" property that is attached to the :Category:Dates page either explicitly or implicitly. Personally I'd think the ideal would be to have MVPs that are queriable in the normal #ask methods, enhanced to reference a metaproperty for the 'Instances' property that lists the property names by which to retrieve values within each MVP arraymap.
So I'm urging a new data model from the get-go, to arrive at simple reusuable syntax like "End Date.Weekday.Text" -- involving navigation from any page via an End Date property to a :category:Dates object, via a Weekday property to a :category:Weekdays object, then finally to a text property for the name of the day.  Ideally, there'd be a built-in set of date objects that can be referenced by others, whose properties can be extended by a wiki (ie defining additional rdfs:domains for the class), and that can be created as pages wthin a wiki.

My problem with SIOs or MVPs as an n-ary solution is this:
Assume a template for a [[:category:Country]] page named "USA" has:
{{#set_internal:Is president of
|Has name=Ulysses S. Grant
|Has vice president#list=Schuyler Colfax, Henry Wilson
What I want is to do simple housekeeping, like recording [[Ulysses S. Grant]] page's property:President Of = [[USA]], and to set each of the Vice President pages' properties to reflect their relationship to [[Ulysses S. Grant]]. Defining complementary properties gets very messy very fast, so it HAS to be able to be done in the template that creates the SIO.  This can make queries of [[Ulysses S. Grant]] much easier.
I'm thinking an #about function can implicitly update arbitrary pages when in the context of another page, such as setting [[Colfax]] page properties when processing a template embedded in [[USA]]. Provenance fields identifying the data source etc could be collected by the #about function. So to set a complementary property ("Presidency") to the ("Is President Of") property, there'd be something like
{{#set_internal: Is president of :: {{FULLPAGENAME}}#{{prez_name}}}
|Has name={{{prez_name}}}
|Has vice president#list={{{prez_vps|}}}
or to set multiple properties on the target object
|Is president of={{FULLPAGENAME}}
|Has vice president#list={{{prez_vps|}}}
If a Weekday name is being set for a certain date, then:
{{#about: Category:Dates#2010-03-04