From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id BDD2CC0051 for ; Wed, 30 Sep 2020 23:45:16 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id A600685C67 for ; Wed, 30 Sep 2020 23:45:16 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id yqSvdVffyLtd for ; Wed, 30 Sep 2020 23:45:14 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail4.protonmail.ch (mail4.protonmail.ch [185.70.40.27]) by fraxinus.osuosl.org (Postfix) with ESMTPS id BAEB185552 for ; Wed, 30 Sep 2020 23:45:14 +0000 (UTC) Date: Wed, 30 Sep 2020 23:44:59 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail; t=1601509511; bh=TtdE2mEa8z0VkhwrZF/8Riifmh4GFBF7ocUXSrf0Lmc=; h=Date:To:From:Cc:Reply-To:Subject:In-Reply-To:References:From; b=ySE1OZHAomQTWKXS52MuiuEpysmSmsyunUS7atPOVGCbWUyRok842kpalocJ5+P87 MnfyhSFqIODS0v+5SahLugHT25Q43A2T+nytaG+nfdvAky4nL3cE2QtEZ39jX0cCl2 YG90zGGoKoT8Uc0xQ+uzUVi7KdOsM3ZWTmCexz18= To: Mike Brooks From: ZmnSCPxj Reply-To: ZmnSCPxj Message-ID: In-Reply-To: References: <5RgK7X_rcpeMbdOdFxKiWkzg6dVcjD0uF_KI8Wt2w7WCBd7dB552EZuRqNQiBbgF4dGBcojwE9GzdWdJeCNmaAlYGYDMAyz6yzSl2QmLC98=@protonmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Cc: Bitcoin Protocol Discussion , Mike Brooks Subject: Re: [bitcoin-dev] Floating-Point Nakamoto Consensus X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Sep 2020 23:45:16 -0000 Good morning Mike, An observation to be made is that the current "first seen" is more incentiv= e-compatible than floating-point Nakamoto consensus. If a miner A mines a block at height N, then obviously the first block it h= as seen is that block. If due to propagation delays on the network, another miner B mines an alter= native block (let us say with more fitness score, regardless of the details= of the fitness metric you use) at height N, miner A has no incentive to re= ject its own version of that block and mine on top of the miner B alternati= ve version, even if floating-point Nakamoto consensus is deployed by most n= odes. Even if the rest of the mining network is now mining on top of the miner B = version, if miner A chances on another new block at N+1 built on top of its= own version of block N, then it would still win both blocks and earn the b= lock subsidy and fees of two blocks. And since block height, as I understand it, trumps over floating-point Naka= moto consensus, the B version will be reorganized out anyway in that case. If miner A had switched to mining on top of the miner B block, then if it w= on another block at height N+1, it would have lost the block subsidy+fees o= f the lower-scoring miner A block at height N. Thus, floating-point Nakamoto consensus is not incentive-compatible, so I d= oubt it would have any kind of adoption. The problems with stability you mention can be fixed, fairly trivially, by = simply waiting for 3 confirmations rather than just 1 confirmation. In a relativistic universe, information cannot propagate faster than light-= speed, and thus there will always be a communications network delay in prop= agating data. As I see it, floating-point Nakamoto consensus cannot fix this issue, as it= cannot change underlying laws of the universe. If your goal is "stability" of some kind, then there is still always a poss= ibility that two miners on opposite sides of the Earth will create blocks a= t the same height outside of the light cones of each other. In a relativistic universe, this cannot be eliminated unless all miners occ= upy the same physical location, i.e. have centralized in the same mining ha= rdware. One of those two blocks created will, with high probability, have a lower s= core, and thus any nodes in the light cone of the miner of the lower-scored= block will still experience a reorg, as they will first see one block, the= n switch to the higher-scored block when it arrives to them. Thus, floating-point Nakamoto consensus cannot provide complete stability o= f the network, still, as the universe we operate in does not have instantan= eous information transfer. A wise designer of automated systems will ***still*** wait for 3 confirmati= ons before doing anything, and by then, the effects of floating-point Nakam= oto consensus will be literally a thing of the past. Regards, ZmnSCPxj