Re: shapes-ISSUE-11 (S9 impossible): S9 is about existing but unspecified values

So, the idea here is that there are some constraints for a Contract. Then, since a Bond is a subclass of a Contract, one doesn't need to repeat all these constraints, but could simply add an additional constraint specific to Bonds, but not to All Contracts - such as requiring a date.

Correct?


Irene

Sent from my iPhone

> On Feb 12, 2015, at 12:46 PM, Dean Allemang <dallemang@workingontologist.com> wrote:
> 
> The spirit of the original story is just the inheritance of further restrictions from "not required" to "required".  For a Contract in general, the end date is no required, but for a Bond, it is.   This is even summarized in the original wiki (I think by pfps) in the sentence, "The larger requirement here is restriction refinement in subclasses"
> 
> 
> From a Shapes point of view, I think it is correct to say that it is impossible to say, "An end date exists, but we haven't specified it" (that sounds like an open-world statement, and I think Shapes makes close-world statements).  If that is the aspect that is deemed "impossible" here, then I concur.
> 
> 
> My point in telling the story may be subsumed elsewhere; it is just that it should be possible to extend a shape that has no requirement for something being filled in (in this example, that's end date) by adding a requirement (e.g., in a sub-shape) that it does have to be specified (and perhaps has other constraints, e.g., end-date should come after start-date). 
> 
> This story was intended as an example; I would not be surprised if the principle for which it is an example has been stated more generally elsewhere. 
> 
> 
> Dean
> 
> 
> 
> 
> 
>> On Wed, Jan 14, 2015 at 4:26 PM, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
>> The problem is that some of S9 appears to be asking for a constraint that states that a contract can have a property value for its end date.  This is different from the ICV constraint provided for bonds, which requires a specified value for the end date.
>> 
>> What would a constraint that required that it was possible to have a value for a property look like?  What would it mean?
>> 
>> peter
>> 
>>> On 01/09/2015 03:41 PM, Dean Allemang wrote:
>>> The issue that S9 is about (as Peter outlines here
>>> https://www.w3.org/2014/data-shapes/wiki/User_Stories#S9:_Contract_time_intervals)
>>> is that it should be possible to add constraints in subclasses where none
>>> existed above.  The ICV example on that page seems to address this quite
>>> directly; at one level, it doesn't represent a constraint, while at the next
>>> level down, it does.  The meaning of this might not be fully clear - I have
>>> added a paragraph to the description on the Stories page that I hope clarifies
>>> it.  Basically, it seems to me that the ICV code has got it right.
>>> 
>>> So, far from being impossible, it seems that there is a solution presented
>>> right on the wiki.
>>> 
>>> On Thu, Dec 18, 2014 at 7:10 PM, RDF Data Shapes Working Group Issue Tracker
>>> <sysbot+tracker@w3.org <mailto:sysbot+tracker@w3.org>> wrote:
>>> 
>>>     shapes-ISSUE-11 (S9 impossible): S9 is about existing but unspecified values
>>> 
>>>     http://www.w3.org/2014/data-shapes/track/issues/11
>>> 
>>>     Raised by: Peter Patel-Schneider
>>>     On product:
>>> 
>>>     Story S9
>>>     https://www.w3.org/2014/data-shapes/wiki/User_Stories#S9:_Contract_time_intervals
>>>     appears to require constraints that state that a property has a value but
>>>     this value is not specified in the graph.  Do any proposals cover this
>>>     requirement?  Is this a constraint at all?
>