Re: [Din] draft-mazieres-dinrg-scp-04 (page 16) setting preparedPrime

David Mazieres <> Sat, 29 September 2018 01:46 UTC

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From: David Mazieres <>
To: Piers Powlesland <>,
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Date: Fri, 28 Sep 2018 18:46:06 -0700
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Subject: Re: [Din] draft-mazieres-dinrg-scp-04 (page 16) setting preparedPrime
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Piers Powlesland <> writes:

> In the section "preparedPrime", I'm wondering if the "highest accepted
> prepared ballot", is referring to a concrete ballot that has been seen
> or a ballot within the conceptual space of ballots?
> For example, if we consider a system with 3 possible values x, y and z and
> x<y<z. If you imagine we have p == (4,z) and we see blocking threshold for
> (3,x) and so set p' == (3,x) if you consider the ballots that have been
> accepted aborted through p and p', you can see that all the ballots required to
> be aborted in order for (3,y) to be considered prepared have been aborted. Do
> we now set p' to (3,y) since (3,y) is greater than (3,x) ?

Thanks for raising the point.  The short answer is that it doesn't
matter--the protocol works either way.

The slightly longer answer, which someone recently pointed out to me, is
that because of this fact, it is actually wasteful to send around the
value of preparedPrime, rather than just the counter.  So the next
revision of the draft will probably address this question...