From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1VeHgz-0006WK-EN for bitcoin-development@lists.sourceforge.net; Thu, 07 Nov 2013 04:59:41 +0000 X-ACL-Warn: Received: from serv.jerviss.org ([12.47.47.47] helo=inana.jerviss.org) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1VeHgw-0002Bq-0Q for bitcoin-development@lists.sourceforge.net; Thu, 07 Nov 2013 04:59:41 +0000 Received: from [10.8.2.254] ([192.151.168.109]) (username: kjj authenticated by PLAIN symmetric_key_bits=0) by inana.jerviss.org (8.13.6/8.12.11) with ESMTP id rA74xUpb020393 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 6 Nov 2013 22:59:30 -0600 Message-ID: <527B1E30.9090800@jerviss.org> Date: Wed, 06 Nov 2013 22:59:28 -0600 From: Kyle Jerviss User-Agent: Mozilla/5.0 (Windows NT 5.2; WOW64; rv:25.0) Gecko/20100101 SeaMonkey/2.22 MIME-Version: 1.0 To: Peter Todd , Bitcoin Dev References: <5279D49D.5050807@jerviss.org> <20131107034404.GA5140@savin> <527B13EC.7020708@jerviss.org> <20131107043310.GA30788@savin> In-Reply-To: <20131107043310.GA30788@savin> Content-Type: multipart/alternative; boundary="------------040109010407010309060007" Received-SPF: pass (inana.jerviss.org: 192.151.168.109 is authenticated by a trusted mechanism) X-Spam-Score: -0.5 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. 0.0 URIBL_BLOCKED ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [URIs: doubleclick.net] -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 1.0 HTML_MESSAGE BODY: HTML included in message X-Headers-End: 1VeHgw-0002Bq-0Q Subject: Re: [Bitcoin-development] we can all relax now X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 07 Nov 2013 04:59:41 -0000 This is a multi-part message in MIME format. --------------040109010407010309060007 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Each block that you solve has a reward. In practice, some blocks will be orphaned, so the expected reward is slightly less than the nominal reward. Each second that you delay publishing a block, the expected reward drops somewhat. On an infinite timeline, the total reward approaches the expected reward. But reality is discrete, and zero tends to be a brick wall. If you delay publishing a block, you will get either the nominal reward, or zero, not some fraction in between. And if your personal random walk involves an excursion through negative land, you may not stick around long enough for it to come back. Thus, a positive expected value is not sufficient for some strategy to be a good one. Peter Todd wrote: > On Wed, Nov 06, 2013 at 10:15:40PM -0600, Kyle Jerviss wrote: >> You are ignoring the gambler's ruin. We do not operate on an >> infinite timeline. If you find a big pool willing to try this, >> please give me enough advance warning to get my popcorn ready. > Gamblers ruin has nothing to do with it. > > At every point you want to evaluate the chance the other side will get > ahead, vs. cashing in by just publishing the blocks you have. (or some > of them) I didn't mention it in the analysis, but obviously you want to > keep track of how much the blocks you haven't published are worth to > you, and consider publishing some or all of your lead to the rest of the > network if you stand to lose more than you gain. > > Right now it's a mostly theoretical attack because the inflation subsidy > is enormous and fees don't matter, but once fees do start to matter > things get a lot more complex. An extreme example is announce/commit > sacrifices to mining fees: if I'm at block n+1, the rest of the network > is at block n, and there's a 100BTC sacrifice at block n+2, I could > easily be in a situation where I have zero incentive to publish my block > to keep everyone else behind me, and just hope I find block n+2. If I > do, great! I'll immediately publish to lock-in my winnings and start > working on block n+3 > > > Anyway, my covert suggestion that pools contact me was more to hopefully > strike fear into the people mining at a large pool and get them to > switch to a small one. :) If everyone mined solo or on p2pool none of > this stuff would matter much... but we can't force them too yet. > > > > ------------------------------------------------------------------------------ > November Webinars for C, C++, Fortran Developers > Accelerate application performance with scalable programming models. Explore > techniques for threading, error checking, porting, and tuning. Get the most > from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk > > > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development --------------040109010407010309060007 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit
Each block that you solve has a reward.  In practice, some blocks will be orphaned, so the expected reward is slightly less than the nominal reward.  Each second that you delay publishing a block, the expected reward drops somewhat.

On an infinite timeline, the total reward approaches the expected reward.  But reality is discrete, and zero tends to be a brick wall.  If you delay publishing a block, you will get either the nominal reward, or zero, not some fraction in between.  And if your personal random walk involves an excursion through negative land, you may not stick around long enough for it to come back.

Thus, a positive expected value is not sufficient for some strategy to be a good one.

Peter Todd wrote:
On Wed, Nov 06, 2013 at 10:15:40PM -0600, Kyle Jerviss wrote:

You are ignoring the gambler's ruin. We do not operate on an
infinite timeline.  If you find a big pool willing to try this,
please give me enough advance warning to get my popcorn ready.

Gamblers ruin has nothing to do with it.

At every point you want to evaluate the chance the other side will get
ahead, vs. cashing in by just publishing the blocks you have. (or some
of them) I didn't mention it in the analysis, but obviously you want to
keep track of how much the blocks you haven't published are worth to
you, and consider publishing some or all of your lead to the rest of the
network if you stand to lose more than you gain.

Right now it's a mostly theoretical attack because the inflation subsidy
is enormous and fees don't matter, but once fees do start to matter
things get a lot more complex. An extreme example is announce/commit
sacrifices to mining fees: if I'm at block n+1, the rest of the network
is at block n, and there's a 100BTC sacrifice at block n+2, I could
easily be in a situation where I have zero incentive to publish my block
to keep everyone else behind me, and just hope I find block n+2. If I
do, great! I'll immediately publish to lock-in my winnings and start
working on block n+3


Anyway, my covert suggestion that pools contact me was more to hopefully
strike fear into the people mining at a large pool and get them to
switch to a small one. :) If everyone mined solo or on p2pool none of
this stuff would matter much... but we can't force them too yet.




------------------------------------------------------------------------------
November Webinars for C, C++, Fortran Developers
Accelerate application performance with scalable programming models. Explore
techniques for threading, error checking, porting, and tuning. Get the most 
from the latest Intel processors and coprocessors. See abstracts and register
http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk


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