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Date: Sun, 13 Dec 2015 02:07:36 +0000
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From: Gregory Maxwell <greg@xiph.org>
To: Vincent Truong <vincent.truong@procabiak.com>
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Cc: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Forget dormant UTXOs without confiscating bitcoin
Precedence: list

On Sun, Dec 13, 2015 at 1:00 AM, Vincent Truong via bitcoin-dev
<bitcoin-dev@lists.linuxfoundation.org> wrote:
> have run a node/kept their utxo before they were aware of this change and
> then realise miners have discarded their utxo. Oops?

I believe you have misunderstood jl2012's post.  His post does not
cause the outputs to become discarded. They are still spendable,
but the transactions must carry a membership proof to spend them.
They don't have to have stored the data themselves, but they must
get it from somewhere-- including archive nodes that serve this
purpose rather than having every full node carry all that data forever.

Please be conservative with the send button. The list loses its
utility if every moderately complex idea is hit with reflexive
opposition by people who don't understand it.

Peter Todd has proposed something fairly similar with "STXO
commitments". The primary argument against this kind of approach that
I'm aware of is that the membership proofs get pretty big, and if too
aggressive this trades bandwidth for storage, and storage is usually
the cheaper resource. Though at least the membership proofs could be
omitted when transmitting to a node which has signaled that it has
kept the historical data anyways.