Re: Extended Relations + Constraints On Constraints proposal

> On 23 Jan 2017, at 20:02, Michael Steidl (IPTC) <mdirector@iptc.org> wrote:
> 
> * sorry, but I can’t follow this detail in the section about Extended Relations: “… each left and right operand would be two constraint objects …”. Having a look into [1] I would formulate: “a constraint could have other constraints as objects of the left and the right operand and the operator of this constraint sets a relationship between these two other constraints”. Did I get [1] right?

Yes. The left and right operands are constraint objects.

>  * re “constraint on constraint”: I understand Renato’s suggestion as defining a sequence of constraints: first comes constraint c1 and if it is met next comes constraint c2 (… and so on). By my understanding of the term “depend” it links constraints but doesn’t set a sequence. I suggest as new Constraint property hasPriorConstraint and its object must be another constraint of this permission or duty which must be processed prior to this one – a processor would have to go back to the starting sequence. 

I am more than happy to use a term with a better meaning than “dependsOn” ;-)
What I would not like to see is getting into explicit sequencing/numbering of constraints, first because we don’t have a use case for it, second, it makes processing harder, and third, we did it in ODRL V1.1 and took it out ;-)

>  
> * re “c1 odrl:dependsOn c2” = “constraint 1 depends on constraint 2”: wasn’t the intention to say “constraint 2 depends on constraint 1” = the subject and the object of the triple should be switched. 

Yes, so as above, “dependsOn” is not the correct term…what’s the opposite of dependsOn?


Renato