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Re: [Din] Quorum slice representation in revised SCP draft draft-mazieres-dinrg-scp-02

Piers Powlesland <pierspowlesland@gmail.com> Wed, 13 June 2018 18:55 UTC

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From: Piers Powlesland <pierspowlesland@gmail.com>
Date: Wed, 13 Jun 2018 19:55:28 +0100
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To: David Mazieres expires 2018-09-10 PDT <mazieres-35dxq5brxkqbm7z745zavx7wdi@temporary-address.scs.stanford.edu>
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Subject: Re: [Din] Quorum slice representation in revised SCP draft draft-mazieres-dinrg-scp-02
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Thanks David,

That makes a bunch of sense.

If I did want to encode a bunch of explicit slices in a manner similar to
that discussed in the whitepaper using the SCPQuorumSet structure (
https://tools.ietf.org/html/draft-mazieres-dinrg-scp-02#section-3.3). I
guess I could have a top level set with the threshold set to 1 and then
encode each quorum slice in separate SCPQuorumSet1 instances each of which
would have the threshold set to the length of their validators.

Reading that section again I'm wondering why only 2 levels of nesting are
allowed?


On Wed, Jun 13, 2018 at 4:01 AM, David Mazieres <
dm-list-ietf-ilc@scs.stanford.edu> wrote:

> Piers Powlesland <pierspowlesland@gmail.com> writes:
>
> > Hi all,
> >
> >
> > The description of a node's quorum slices in the white paper is a
> > collection of sets of nodes for which any set is sufficient to convince
> the
> > node of system wide agreement. I would represent this as a list of lists.
> >
> > So I'm wondering why the recursive SCPQuorumSet struct was chosen to
> > represent quorum slices?
>
> The whitepaper uses sets of sets for the proofs because it's the most
> general thing possible.  However, often people want a very large number
> of quorum slices--like, say, k of n nodes.  For, say, a 7-out-of-10
> configuration, that's 120 different quorum slices, which would be quite
> unwieldy to ship around as a list of lists.
>
> David
>

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