[Odrl-version2] Constraints on duties - I think I've got it now...
Vicky Weissman
vickyw at cs.cornell.edu
Wed Jun 21 04:28:43 EST 2006
Hi,
If I understood your last mail correctly, the agreement
Party=Alice
Perm=Download
Asset=F
Duty=d
Duty.Constraint=c
Duty.Relax = false
means that Alice may download F if she has (1) fulfilled duty d at time t and
(2) at time t, constraint c holds. So, if d = "pay 5 Euros" and c is "time
is before June 30, 2006", then Alice may download F if she has already paid 5
euros and that payment was made before June 30, 2006.
Assuming this correct, lets see how the definition plays out in a few other
examples.
Party=Alice
Perm= lock
Asset= f.src
Duty= unLock
Duty.Constraint= within 24 hours
Duty.Relax = true
This means that Alice is allowed to lock the source file f.src, and she can
keep the lock for as long as she wants. However the agreement writer/owner
asks that she release the lock within 24 hours of taking it (i.e., she ought
to - but is not legally required to - unlock within 24 hrs.) Note: I'm
assuming Duties do not have to be payments (as clarified by Susanne) and the
application-specific vocabulary includes the constant
"time_Alice_Last_Locked_f.src", so we can have a constraint "before
time_Alice_Last_Locked_f.src + 24 hrs".
I wonder if duties should have (optional) consequences. For example, maybe
the agreement owner would like to say "Alice may lock f.src; she should
return the lock within 24 hours, and, if she doesn't return the lock, then
she'll be charged one Euro a day". More generally, relaxed duties allow
obligations to hold after the right has been granted/exercised, so I think
it'd make sense (and is often the case in practice) for there to be
consequences to unmet obligations. What do you think?
-----
Party=Alice, Bob
Perm= download
Asset= F
Duty= pays 1 euro
Duty.Constraint= user is over 21
Duty.Relax = false
This means (1) if Alice is over 21, then she may pay 1 euro and, if she pays
the euro, then she may download F. The same is true for Bob. So the
agreement is equivalent to one that says "Alice/Bob may download F if she/he
is over 21 and pays a euro". That is, the agreement is equivalent to
Party=Alice, Bob
Perm= download
Asset= F
Duty= pays 1 euro
Perm.Constraint= user is over 21
Duty.Relax = false
----
(This one's really about parties v. individuals.)
Party=Alice
Perm= download
Asset= F
Duty= pays 1 euro
Duty.Assignee = {Alice, Bob}
Duty.Beneficiary = {Charlie, Dan}
Duty.Relax = false
The agreement says that Alice may download F if {Alice, Bob} has paid 1 euro
to {Charlie, Dan}. Suppose Bob gives a euro to Charlie. Then does it
necessarily follow that {Alice, Bob} has given a euro to {Charlie, Dan} and,
thus, Alice may download F?
Thank you so much for your patience.
Best,
Vicky
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