From: Rusty Russell <rusty@rustcorp.com.au>
To: Jim Posen <jim.posen@gmail.com>,
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
In-Reply-To: <CADZtCShwOV+GuJ5__GMi9hd2_X=BztASPBihDXakU3Mjb39wcQ@mail.gmail.com>
References: <87po25lmzs.fsf@rustcorp.com.au>
	<201805100227.42217.luke@dashjr.org>
	<87vabnq9ui.fsf@rustcorp.com.au>
	<CADZtCShwOV+GuJ5__GMi9hd2_X=BztASPBihDXakU3Mjb39wcQ@mail.gmail.com>
Date: Mon, 21 May 2018 13:14:06 +0930
Message-ID: <87zi0tisft.fsf@rustcorp.com.au>
MIME-Version: 1.0
Content-Type: text/plain
Cc: Matt Corallo <matt@chaincode.com>
Subject: Re: [bitcoin-dev] Making OP_TRUE standard?
Precedence: list

Jim Posen <jim.posen@gmail.com> writes:
> I believe OP_CSV with a relative locktime of 0 could be used to enforce RBF
> on the spending tx?

Marco points out that if the parent is RBF, this child inherits it, so
we're actually good here.

However, Matt Corallo points out that you can block RBF will a
large-but-lowball tx, as BIP 125 points out:

   will be replaced by a new transaction...:

   3. The replacement transaction pays an absolute fee of at least the sum
      paid by the original transactions.

I understand implementing a single mempool requires these kind of
up-front decisions on which tx is "better", but I wonder about the
consequences of dropping this heuristic?  Peter?

Thanks!
Rusty.