Re: Comment on RDF Mapping: variables in sequence pattern

On Wed, Jan 28, 2009 at 04:08, Ian Horrocks
<ian.horrocks@comlab.ox.ac.uk> wrote:

> On 7 Jan 2009, at 18:24, Peter F. Patel-Schneider wrote:

>> A "big club" fix would be to have a global constraint along the lines
>> of:
>>
>>        No blank node can be used in more than once in these patterns.
>>        (This means that all lists are non-cyclic and do not share
>>        tails.)


> The "big club" clearly does the job, is easy to understand, and I don't see
> any serious disadvantages -- am I missing something?

It looks like it's in place in the wiki version of the document.

I think the wording needs some additional tweaking to make clear that
a node can be used multiple times as a list element.  I.e., it should
be permissible for variables y_i , y_j to match the same node and the
current text seems to prevent that.
-- 
Mike Smith

Clark & Parsia

Received on Wednesday, 28 January 2009 15:54:24 UTC