From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 728D6C0859 for ; Fri, 25 Sep 2020 16:33:30 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 49474875DA for ; Fri, 25 Sep 2020 16:33:30 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Cv2SC9dtLg-u for ; Fri, 25 Sep 2020 16:33:29 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by hemlock.osuosl.org (Postfix) with ESMTPS id EFDBA875CD for ; Fri, 25 Sep 2020 16:33:28 +0000 (UTC) Received: from mail-ed1-f41.google.com (mail-ed1-f41.google.com [209.85.208.41]) (authenticated bits=0) (User authenticated as jlrubin@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 08PGXQdd003034 (version=TLSv1/SSLv3 cipher=AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 25 Sep 2020 12:33:27 -0400 Received: by mail-ed1-f41.google.com with SMTP id c8so3121006edv.5 for ; Fri, 25 Sep 2020 09:33:27 -0700 (PDT) X-Gm-Message-State: AOAM530F65bnb7+iBOcYDfkki0fTcCCHRXAMVXhbx35ywFuXv+aJ5GJT OmdEa+Y0J7q7dHPyX+5UkSASRQBJvaA7ubXW8jo= X-Google-Smtp-Source: ABdhPJwyEIDiDths3XZoKF3Ni/+QBc8eyneOwfHWQDRIcKaR5rd5KIac9ZoM1OWC2arMHLRWtLsNrZYZWJe0jPQ4UXI= X-Received: by 2002:a05:6402:1717:: with SMTP id y23mr2324440edu.112.1601051606146; Fri, 25 Sep 2020 09:33:26 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Jeremy Date: Fri, 25 Sep 2020 09:33:14 -0700 X-Gmail-Original-Message-ID: Message-ID: To: bitcoin ml , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="0000000000004063dc05b025e02a" 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: Fri, 25 Sep 2020 16:33:30 -0000 --0000000000004063dc05b025e02a Content-Type: text/plain; charset="UTF-8" If I understand correctly, this is purely a policy level decision to accept first-seen or a secondary deterministic test, but the most-work chain is still always better than a "more fit" but less work chain. In any case, I'm skeptical of the properties of this change. First-seen has a nice property that once you receive a block, you have a substantially reduced incentive to try to orphan it because the rest of the network is going to work on building on that block. With fitness, I have a 50% shot if I mine a block of mine being accepted, so floating point would have the effect of destabilizing consensus convergence at the tip. I could see using a fitness rule like this be useful if you see both blocks within some very small window, e.g., 10 seconds, as it could decrease partition risk if it's likely the orphan was mined within close range of the other. --0000000000004063dc05b025e02a Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
If I und= erstand correctly, this is purely a policy level decision to accept first-s= een or a secondary deterministic test, but the most-work chain is still alw= ays better than a "more fit" but less work chain.

In any ca= se, I'm skeptical of the properties of this change. First-seen has a ni= ce property that once you receive a block, you have a substantially reduced= incentive to try to orphan it because the rest of the network is going to = work on building on that block. With fitness, I have a 50% shot if I mine a= block of mine being accepted, so floating point would have the effect of d= estabilizing consensus convergence at the tip.

I could see using a fi= tness rule like this be useful if you see both blocks within some very smal= l window, e.g., 10 seconds, as it could decrease partition risk if it's= likely the orphan was mined within close range of the other.
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