[cap-talk] Is "Authority" Subjective?

[Toby Murray]

On Fri, 2007-06-22 at 17:00 +0200, Pierre THIERRY wrote:
> Scribit Toby Murray dies 22/06/2007 hora 15:48:
> > Suppose we have 3 objects/subjects/actors/whatever, Alice, Bob and Carol
> > and the system is 
> > 
> > P = aliceInvokesCarol -> carolRespondsToAlice -> bobInvokesCarol -> STOP
> > []
> >     bobInvokesCarol -> STOP
> > 
> > i.e. initially either Alice or Bob can invoke Carol. Once invoked by
> > Alice, Bob can't invoke Carol until she responds to Alice. 
> > 
> > Would you say that Alice can cause Bob to invoke Carol?
> 
> That obviously depends on Carol's code. If Carol is coded to answer to
> Alice's request, then Alice has the authority.

I don't understand. Alice and Bob both have permission to invoke Carol.
She can't refuse invocations from either of them. This is represented by
the possibility of both aliceInvokesCarol and bobInvokesCarol initially.
If Alice invokes Carol first, (ie. aliceInvokesCarol occurs), then Bob
has to wait until the invocation finishes (ie. until
carolRespondsToAlice occurs) until he can invoke Carol himself by
performing bobInvokesCarol.

The point is that one could argue that Alice doesn't have influence over
Bob, except to prevent him from invoking Carol while Alice herself has
Carol invoked. So one might argue that Alice can't cause Bob to invoke
Carol. (This is the original Argument 1)

However (Argument 2), once Alice invokes Carol, she can actually prevent
Bob from invoking Carol if she never partakes in carolRespondsToAlice.
Each event requires both parties to agree to perform it, before it can
be performed. Thus, carolRespondsToAlice can't be performed until both
Alice and Carol are willing to perform it. Hence, if Alice refuses to
partake in carolRespondsToAlice, she can prevent Bob from being able to
invoke Carol. Thus by performing this event, we might say she can cause
Bob to invoke Carol.

So which way is it? I can't decide. (I also don't seem to be able to
explain this very well either. Or maybe I just fail to understand
people's reasonable replies. Apologies either way.)


>  Here we may lack a term
> for "partial" authority: if Carol is coded to answer to the request
> between 8 PM and 7 PM, Alice still has authority, just not as much as if
> Carol answer systematically.
> 
> If Carol is a Caretaker, the usage here on the list was to say that
> Alice has authority until the Caretaker is disabled. Hence calling the
> disabling of the Caretaker "revoking Alice's authority".
> 
> Note that it makes authority undecidable in the general case. Think of a
> proxy that forwards messages randomly... (random authority may be an
> interesting concept)

What I'm after is that if Alice can /ever/ cause Carol to be invoked,
then we consider that Alice has authority to invoke Carol. Even if can
only ever happen once, or in very unlikely circumstances. Later, maybe
I'll be able to tease out different degrees of authority. But for now,
we're just trying to start at the beginning ;)

Cheers

Toby