From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp11.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms0.migadu.com with LMTPS id ON2tKAtl1WFiEgEAgWs5BA (envelope-from ) for ; Wed, 05 Jan 2022 10:29:47 +0100 Received: from aspmx1.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp11.migadu.com with LMTPS id wIwjJgtl1WE2cwAA9RJhRA (envelope-from ) for ; Wed, 05 Jan 2022 10:29:47 +0100 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id 4FD071755C for ; Wed, 5 Jan 2022 10:29:47 +0100 (CET) Received: from localhost ([::1]:46216 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n52c6-0008FI-FE for larch@yhetil.org; Wed, 05 Jan 2022 04:29:46 -0500 Received: from eggs.gnu.org ([209.51.188.92]:49956) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n52bt-0008FA-UI for guix-devel@gnu.org; Wed, 05 Jan 2022 04:29:33 -0500 Received: from world.peace.net ([64.112.178.59]:33404) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n52bs-0000r3-5o for guix-devel@gnu.org; Wed, 05 Jan 2022 04:29:33 -0500 Received: from mhw by world.peace.net with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1n52bo-00071V-4X; Wed, 05 Jan 2022 04:29:28 -0500 From: Mark H Weaver To: Liliana Marie Prikler , zimoun , guix-devel@gnu.org Subject: Re: On raw strings in commit field In-Reply-To: <871r1nawz8.fsf@netris.org> References: <6e451a878b749d4afb6eede9b476e5faabb0d609.camel@gmail.com> <86y243kdoo.fsf@gmail.com> <899587fb6a76ddfa37d197d3d0fd23cdc7ad8592.camel@gmail.com> <867dbmi7pf.fsf@gmail.com> <3d448fe42f0c43574db96fa26aecd7da5fd5a95d.camel@gmail.com> <877dbkmjm9.fsf@netris.org> <762e9fb7116c442bf0f8f63221bf32fa2b77f2cf.camel@gmail.com> <87y240kq2i.fsf@netris.org> <9362c6fb7e34ded5d009c3f79cd18300d6cd539c.camel@gmail.com> <87r19rkx9h.fsf@netris.org> <87r19pbv8y.fsf@netris.org> <87mtkcbedc.fsf@netris.org> <3f947861672144d202a8c736d5e8f2b905c31b66.camel@gmail.com> <871r1nawz8.fsf@netris.org> Date: Wed, 05 Jan 2022 04:28:44 -0500 Message-ID: <87h7aia5ug.fsf@netris.org> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=64.112.178.59; envelope-from=mhw@netris.org; helo=world.peace.net X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: guix-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+larch=yhetil.org@gnu.org Sender: "Guix-devel" X-Migadu-Flow: FLOW_IN X-Migadu-Country: US ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1641374987; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references:list-id:list-help:list-unsubscribe: list-subscribe:list-post; bh=qSarytVVRAv/XPT+1ARbn6P23dTANU4YAjD2lQXf0VY=; b=r6yeD//nrbLvyRsBaQ+elj20gnH9WehZOAel/+2I9WxAfAwdHqsmb0bGXrm3IYe5sMT/vN mhDQzfHGQLtnnVP4TjkTEeftfEILZRgv+b5U0HROgBzWkKJzf2JDwlaU/MvikPMlAiLZ2D XzqXFt4Sudg0eLWL6ltSZRoQsFi2grbrq3NLt9hrLPc+mt+SavAAFAvwv/OVxUdnXBYAdR BlK+vbZMrLm8jikHIbosRSzmFwtXMr16Y/L3DD00HwktqnOQP1W25Z5/77ybSlzM9IOm/i EcdwmDI/EFb6IsDNPcTTzA50wGURVaCcy5pPbY53bqcmeGXBrrqWVb1SAJ71HA== ARC-Seal: i=1; s=key1; d=yhetil.org; t=1641374987; a=rsa-sha256; cv=none; b=oagO0I6xCfmh2H+74Js+Sxl4hMi0O2RN9Dtnkf7w4QiSdFUzf0QbyipuR9GIYELGrRT2DW feIk2fdCDD+yS/wO3//kbPISQkY2tckmwTgf4QQTs2QGY3rJInNit461Etf9zuNu5behX6 TbFZuzXq4TtHdcchAnPhNzoUFxFhfI7hrCc36CNM8zwT79+Mqpq0k/eIKx0edeatg41jvH jbWOMZ1PujWUFtxA0be+4zgfskDLcmUBXhSMlaOlEj5SDkb4GplPE3s8mdZx8hRLc0AQPz gGajSIfggHwXPc0zqYTWS2IwNbLAIKikv+csfu1hNEHDFlEAedihil6SLDzmyw== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=none; dmarc=none; spf=pass (aspmx1.migadu.com: domain of "guix-devel-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-devel-bounces+larch=yhetil.org@gnu.org" X-Migadu-Spam-Score: -3.60 Authentication-Results: aspmx1.migadu.com; dkim=none; dmarc=none; spf=pass (aspmx1.migadu.com: domain of "guix-devel-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-devel-bounces+larch=yhetil.org@gnu.org" X-Migadu-Queue-Id: 4FD071755C X-Spam-Score: -3.60 X-Migadu-Scanner: scn0.migadu.com X-TUID: piKFgUsDDEQp Hi Liliana, Earlier, I wrote: > Sorry, but this is not even close to a valid argument that the set of > possible push actions to a Git repo is uncountable. In fact, it's quite > easy to prove that the set is countable. Any mathematician will know this. I suppose I should give a proof. I'll give two proofs. First I'll give a very simple proof that depends on assuming that every push action can be uniquely represented as a message of finite length. You may imagine this representation as being something like the output of "git log --patch --format=fuller" but with _every_ piece of information that git has about the pushed commits included. Better yet, you could imagine the representation as being closer to what git push actually sends to the server: a set of references to mutate, and a pack of objects reachable by those references. As an optimization, there is a more complex two-way exchange to avoid sending objects that the server already has, but for purposes of this proof you could imagine eliminating that optimization. Anyway, if you'll accept that every push action can be represented as a message of finite length, then the proof is very simple: Observe that there exists a one-to-one correspondence between push actions and a subset of messages of finite length, and moreover that there exists a one-to-one correspondence between messages of finite length and a subset of the natural numbers. Therefore, there exists a one-to-one correspondence between push actions and a subset of the natural numbers. Thus, the set of push actions is countable, by definition. Q.E.D. =-=-= If you don't accept the assumption above, here's a more detailed proof that could be adapted to *any* kind of action that can be communicated over a digital communications channel in finite time: First, note that every push action can be performed by exchanging a finite number of messages of finite length between the client and server, hereafter referred to as a "finite exchange". Let P be the set of possible push actions. Let V be the subset of finite exchanges that represent a push action, hereafter referred to as a "valid exchange". Let f : V -> P be a function that maps valid exchanges to the push actions that they represent. Observe that f is surjective, i.e. for all p in P, there exists v in V such that f(v) = p. In other words, for every push action, there exists at least one valid exchange that represents that push action. Since f : V -> P is a surjective function, it follows that the cardinality of V is greater than or equal to the cardinality of P. Now, note that any valid exchange can be represented as a bit string of finite length, and therefore as a natural number. (There are many ways to do this; the details are left as an exercise). Therefore, the set V of valid exchanges is in one-to-one correspondence with a subset of the natural numbers, and is therefore countable, by definition. Since V is countable, and it has cardinality greater than or equal to the cardinality of P, it follows that P (the set of push actions) is also countable. Q.E.D. Mark -- Disinformation flourishes because many people care deeply about injustice but very few check the facts. Ask me about .