[Odrl-version2] RE: ODRL-Version2 Digest, Vol 17, Issue 3

[Renato Iannella]

On 6 Jun 2006, at 12:32, Vicky Weissman wrote:

> I'm sorry but I still don't understand.  More precisely, your  
> encoding makes perfect sense, and the question I was trying to  
> answer using the example is still open.  Let me try to ask the  
> question again.  Suppose an agreement gives Alice  permission to  
> download a file f; this policy is associated with the duty "pay 5  
> dollars"; the Boolean flag is not set (so the duty must be  
> fulfilled before the permission is granted); and this duty is  
> associated with a constraint c.  Which of the following should we  
> conclude (or should we conclude something else)?
>
> (a) If c holds and Alice pays 5 dollars, then she may download f.
>
> (b) If c does not hold, then Alice may download f; if c does hold,  
> then Alice may download f if she pays 5 dollars.
>
> Note: (a) suggests that a constraint c associated with a duty is  
> the same as c associated with a permission; (b) suggests that the  
> constraint on the duty says whether the duty must be fulfilled;  
> and, as far as I can tell, neither interpretation can be used to  
> say that Alice may download f (now) if she pays 5 dollars by the  
> end of the month (sometime in the near future).
Ok - lets define these as:

Party=Alice
Perm=Download
Asset=F
Duty=Pay[amt=5]
Duty.Constraint=Date[before30June06]

Given this, Statement (a) above is OK.
The first part of Statement (b) is not OK (since the Duty.Constraint  
is false).
The second part of Statement (b) is OK.

I think you are asking what is the impact/difference between a  
Constraint on a Duty and on a Permission (and is there any difference)

In the above case, as long as Duty and Duty.Constraint are fulfilled,  
then you can do Perm (ie download) any time after that.

Consider the following similar example:

Party=Alice
Perm=Download
Perm.Constraint=Date[before30June06]
Asset=F
Duty=Pay[amt=5]

In this case, as long as Duty is fulfilled, you can do Perm, BUT you  
need to do it (download) before 30June06.
So, if you paid $5 after that date, you still could not download the  
Asset (doh!)


Cheers

Renato Iannella
ODRL Initiative
http://odrl.net


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