On Tue, Jan 23, 2018 at 10:49:34PM +0000, Gregory Maxwell via bitcoin-dev wrote:
> On Tue, Jan 23, 2018 at 10:19 PM, Rhavar via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
> > Interesting. I didn't think about this before, but it seems like bip125 is
> > rather incentive incompatible right now? If we're assuming a competitive
> > mempool, it really doesn't seem generally rational to accept a replacement
> > transaction of a lower fee rate.
> 
> BIP125 replacement requires that the fee rate increases.  The text of
> the BIP document is written in a confusing way that doesn't make this
> clear.

In fact I considered only requiring an increase in fee rate, based on the
theory that if absolute fee went down, the transaction must be smaller and thus
miners could overall earn more from the additional transactions they could fit
into their block. But to do that properly requires considering whether or not
that's actually true in the particular state the mempool as a whole happens to
be in, so I ditched that idea early on for the much simpler criteria of both a
feerate and absolute fee increase.

-- 
https://petertodd.org 'peter'[:-1]@petertodd.org