Re: caution on using EXISTS and pre-binding in SHACL

Peter, I greatly appreciate the analyses you've done of SHACL, but 
because I know less than zero about SPARQL pre-binding I'm afraid I need 
to ask you a couple of questions that I am sure you think you have 
already answered:

Is the problem the way in which pre-binding has been implemented in 
SHACL, or is pre-binding, in your opinion, not viable at all?

If pre-binding is not viable, is SHACL still viable?

Thanks,
kc

On 6/19/16 2:05 PM, Peter F. Patel-Schneider wrote:
> I spent some time last week turning over rocks in the SPARQL specification
> to see what's underneath them.  I found a lot of ugly stuff there,
> particularly related to EXISTS.  It is even the case that different SPARQL
> impleentations diverge on the behaviour of EXISTS.
>
> This matters to SHACL in two ways.  First, EXISTS is used in the definitions
> of many SHACL core constraint components.  I don't know if any of these uses
> of EXISTS hit any problems, but I don't think that I have found all the
> problems with EXISTS.  Even if the core constraint components don't hit any
> problems, EXISTS is going to be important for extension constraint
> components and these could easily hit problems with EXISTS.  Second, SHACL
> pre-binding is defined in a way very similar to the way that EXISTS is
> defined so it is entirely possible that the definition of pre-binding has
> problems.  Pre-binding is central to the definition of SHACL and central
> to the extension mechanism in SHACL so its definition is going to have be
> examined extremely closely.
>
> This all is in addition to the problems in the definition of pre-binding
> that I have already pointed out.
>
>
> Peter F. Patel-Schneider
> Nuance Communications
>
>

-- 
Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600

Received on Monday, 20 June 2016 21:16:05 UTC