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Date: Fri, 8 May 2015 16:54:05 +0200
Message-ID: <CAOoPuRZo6M1-XTYk6LebADHwQVwKEOYtaHGvEoRkk5AfevvJYw@mail.gmail.com>
From: Benjamin <benjamin.l.cordes@gmail.com>
To: Tier Nolan <tier.nolan@gmail.com>
Content-Type: text/plain; charset=UTF-8
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Assurance contracts to fund the network
 with OP_CHECKLOCKTIMEVERIFY
Precedence: list

>> Imagine a group of 1000 people who want to make a donation of 50BTC to something.  They all way that they will donate 0.05BTC, but only if everyone else donates.

It still isn't perfect.  Everyone has an incentive to wait until the
last minute to pledge. <<

AC does not solve the problem. AC works if people gain directly from
the payment. Imagine a group of people paying tax - nobody gains from
paying it. You have to actually need to enforce negative outcomes to
enable it (jail for tax fraud). Hence in Bitcoin we have the enforced
subsidy. AFAIK the problem of how to incentivize transaction
verification without subsidy is unsolved. Who determines a fair price?
People around here should study more economics, game theory, etc.
instead of debating low level encodings all the time.

On Fri, May 8, 2015 at 4:15 PM, Tier Nolan <tier.nolan@gmail.com> wrote:
> Just to clarify the process.
>
> Pledgers create transactions using the following template and broadcast
> them.  The p2p protocol could be modified to allow this, or it could be a
> separate system.
>
> Input: 0.01 BTC
> Signed with SIGHASH_ANYONE_CAN_PAY
>
> Output 50BTC
> Paid to: <1 million> OP_CHECKLOCKTIMEVERIFY OP_TRUE
>
> Output 0.01BTC
> Paid to OP_TRUE
>
> This transaction is invalid, since the inputs don't pay for the output.  The
> advantage of the sighash "anyone can pay" field is that other people can add
> additional inputs without making the signature invalid.  Normally, any
> change to the transaction would make a signature invalid.
>
> Eventually, enough other users have added pledges and a valid transaction
> can be broadcast.
>
> Input: 0.01 BTC
> Signed with SIGHASH_ANYONE_CAN_PAY
>
> Input: 1.2 BTC
> Signed with SIGHASH_ANYONE_CAN_PAY
>
> Input: 5 BTC
> Signed with SIGHASH_ANYONE_CAN_PAY
>
> <etc>
>
> Input: 1.3 BTC
> Signed with SIGHASH_ANYONE_CAN_PAY
>
> Output 50BTC
> Paid to: <1 million> OP_CHECKLOCKTIMEVERIFY OP_TRUE
>
> Output 0.01BTC
> Paid to OP_TRUE
>
> This transaction can be submitted to the main network.  Once it is included
> into the blockchain, it is locked in.
>
> In this example, it might be included in block 999,500.  The 0.01BTC output
> (and any excess over 50BTC) can be collected by the block 999,500 miner.
>
> The OP_CHECKLOCKTIMEVERIFY opcode means that the 50BTC output cannot be
> spent until block 1 million.  Once block 1 million arrives, the output is
> completely unprotected.  This means that the miner who mines block 1 million
> can simply take it, by including his own transaction that sends it to an
> address he controls.  It would be irrational to include somebody else's
> transaction which spent it.
>
> If by block 999,900, the transaction hasn't been completed (due to not
> enough pledgers), the pledgers can spend the coin(s) that they were going to
> use for their pledge.  This invalidates those inputs and effectively
> withdraws from the pledge.
>
> On Fri, May 8, 2015 at 11:01 AM, Benjamin <benjamin.l.cordes@gmail.com>
> wrote:
>>
>> 2. "A merchant wants to cause block number 1 million to effectively
>> have a minting fee of 50BTC." - why should he do that? That's the
>> entire tragedy of the commons problem, no?
>
>
> No, the pledger is saying that he will only pay 0.01BTC if the miner gets a
> reward of 50BTC.
>
> Imagine a group of 1000 people who want to make a donation of 50BTC to
> something.  They all way that they will donate 0.05BTC, but only if everyone
> else donates.
>
> It still isn't perfect.  Everyone has an incentive to wait until the last
> minute to pledge.