On Sun, Sep 27, 2015 at 2:39 AM, Gregory Maxwell via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> Unless the weak block transaction list can be a superset of the block
> transaction list size proportional propagation costs are not totally
> eliminated.
>

The POW threshold could be dynamic.  The first weak-block that builds on a
new block could be forwarded with a smaller target.

This reduces  the window size until at least one weak block is propagated.

The change in threshold could be time based (for the first 30 seconds or
so).  This would cause a surge of traffic when a new block once a new block
has propagated, so perhaps not so good an idea.


> As even if the weak block criteria is MUCH lower than the block
> criteria (which would become problematic in its own right at some
> point) the network will sometimes find blocks when there hasn't been
> any weak block priming at all (e.g. all prior priming has made it into
> blocks already).
>

If there is a transaction backlog, then miners could forward merkle
branches with transactions in the memory pool with a commitment in the
coinbase.