Pi币白皮书中文版

介绍

问题：第一代加密货币的可访问性

解决方案：Pi-Mining移动化

Pi经济模型：平衡稀缺性和获取性

实用程序：在p2p中实现未开发资源的货币化

治理-人民的货币

路线图/部署计划

草案1 2019年3月14日

前言

随着世界变得越来越数字化，加密货币是货币进化的下一个自然步骤。π是第一种面向日常生活的数字货币，代表着全球采用加密货币的重大进步。

我们的使命：建立一个加密货币和智能合约平台，由日常生活中的人们安全和操作。

我们的愿景：建立世界上最具包容性的点对点市场，由全球使用最广泛的加密货币Pi推动

高级读者免责声明：由于Pi的使命是尽可能包容，我们将借此机会向我们的区块链新手介绍兔子洞：）

简介：为什么加密货币很重要

目前，我们的日常金融交易依赖于可信的第三方来保持交易记录。例如，当您进行银行交易时，银行系统会保留记录并保证交易安全可靠。同样，当Cindy使用PayPal向Steve转账5美元时，PayPal保持着从Cindy账户借记5美元、贷记Steve账户贷记5美元的中央记录。银行、PayPal和当前经济体系的其他成员等中介机构在规范世界金融交易方面发挥着重要作用。

但是，这些可信中介机构的作用也有局限性：

1、不公平的价值获取。这些中介机构积累了数十亿美元的财富创造（贝宝市值约为1300亿美元），但实际上并没有将任何东西传递给他们的客户——当地的普通百姓，他们的资金在全球经济中占据了相当大的比例。越来越多的人落后了。

2、费用。银行和公司为促进交易收取大量费用。这些费用往往不成比例地影响到低收入人群，他们拥有的替代品最少。

3、审查制度。如果某个受信任的中介机构决定您不能移动您的资金，它可以对您的资金移动施加限制。

4、允许的。可信的中间人充当守门员，可以任意阻止任何人成为网络的一部分。

5、假名。在隐私问题变得越来越紧迫的时候，这些强大的看门人可能会意外地披露——或者强迫你披露——更多关于你自己的财务信息。

比特币的“点对点电子现金系统”（peer-to-peer electronic cash system）于2009年由一位匿名程序员（或群组）Satoshi Nakamoto推出，是货币自由的分水岭。历史上第一次，人们可以安全地交换价值，而不需要第三方或可信的中间人。用比特币支付意味着像史蒂夫和辛迪这样的人可以直接支付对方，绕过机构收费、障碍和入侵。比特币确实是一种无国界的货币，为新的全球经济提供动力和连接。

分布式账本简介

比特币通过使用分布式记录实现了这一历史壮举。虽然目前的金融系统依赖于传统的中央真实记录，但比特币记录是由一个分布式的“验证器”社区维护的，验证器访问和更新这个公共分类账。想象一下，比特币协议是一个全球共享的“谷歌表单”，它包含一个交易记录，由这个分布式社区验证和维护。

比特币（和通用区块链技术）的突破之处在于，即使记录是由一个社区维护的，但该技术使他们能够始终就真实交易达成共识，确保作弊者无法记录虚假交易或超越系统。这一技术进步允许在不损害交易性金融安全的情况下移除集中中介机构。

分布式账本的好处

除了分散化，比特币，或者一般的加密货币，都有一些很好的特性，这些特性使得货币更加智能和安全，尽管根据协议的不同实现，不同的加密货币在某些特性上可能更强，而在其他特性上可能更弱。加密货币保存在加密钱包中，密码钱包由一个可公开访问的地址标识，并由一个非常强大的私有密码（称为私钥）进行保护。此私钥以加密方式签署交易，实际上不可能创建欺诈性签名。这提供了安全性和不可见性。与传统的银行账户可以被政府当局查封不同，钱包里的加密货币没有你的私人钥匙，任何人都不能拿走。加密货币由于其分散的特性而不受审查，因为任何人都可以将交易提交给网络中的任何计算机进行记录和验证。Cryptocurrency事务是不可变的，因为每个事务块表示在此之前存在的所有先前块的加密证明（散列）。一旦有人给你寄钱，他们就不能偷回给你的钱（即区块链中没有跳票）。一些加密货币甚至可以支持原子交易。建立在这些加密货币之上的“智能合约”不仅依赖法律来执行，而且直接通过可公开审计的代码来执行，这使得它们不可信任，并有可能摆脱许多企业的中间人，例如房地产托管。

保护分布式账本（采矿）

维护分布式交易记录的一个挑战是安全性——特别是，如何在防止欺诈活动的同时拥有一个开放和可编辑的分类账。为了应对这一挑战，比特币引入了一种称为挖掘（使用一致算法“工作证明”）的新流程，以确定谁是“受信任的”来更新交易的共享记录。

您可以将采矿视为一种经济游戏，它迫使“验证者”在尝试将交易添加到记录中时证明其价值。要获得资格，验证器必须解决一系列复杂的计算难题。首先解决谜题的验证器通过允许发布最新的交易块获得奖励。发布最新的交易块允许验证器“挖掘”一个块奖励-目前是12.5比特币（或写作时约40000美元）。

这个过程是非常安全的，但它需要巨大的计算能力和能源消耗，因为用户本质上是“烧钱”来解决为他们赚取更多比特币的计算难题。烧钱与回报的比率是如此的惩罚性，以至于在比特币记录中公布诚实的交易总是符合验证器的自身利益。

问题：权力和金钱的集中使得第一代加密货币遥不可及

在比特币诞生的早期，只有少数人在验证交易并挖掘第一个区块时，任何人只要在个人电脑上运行比特币挖掘软件就可以赚取50比特币。随着人民币开始走红，聪明的矿工们意识到，如果他们有一台以上的电脑来开采，他们可以赚更多。

随着比特币价值的持续增长，整个公司都开始涌向我的领域。这些公司开发了专门的芯片（“ASIC”），并利用这些ASIC芯片建造了大量的服务器场来开采比特币。众所周知，这些巨大的矿业公司的出现推动了比特币淘金热，使得普通人很难为网络做出贡献并获得回报。他们的努力也开始消耗越来越多的计算能源，导致世界各地的环境问题日益严重。

比特币开采的便利性以及随后比特币矿场的兴起，很快在比特币的网络中产生了生产力量和财富的大规模集中。为了提供一些背景信息，87%的比特币现在归其网络的1%所有，其中许多在早期是免费开采的。另一个例子是，比特币最大的采矿业务之一Bitmain已经赚取了数十亿美元的收入和利润。

比特币网络的权力集中，让普通人很难、很贵。如果你想获得比特币，最简单的选择是：

1、我自己的。只需连接专门的硬件（如果你感兴趣的话，这里有一个亚马逊平台！）去城里。只要知道，既然你将与来自世界各地的大型服务器农场竞争，消耗的能源与瑞士一样多，你就无法开采出更多的资源

2、在交易所购买比特币。今天，你可以在写作时以3500美元/枚的单价购买比特币（注：你可以购买少量比特币！）当然，你这样做也会冒很大的风险，因为比特币的价格波动很大。

比特币是第一个展示加密货币如何扰乱当前金融模式，使人们能够在没有第三方阻碍的情况下进行交易的公司。自由、灵活性和隐私的增加继续推动着数字货币作为一种新规范的必然行进。尽管比特币有其好处，但它（可能是无意中）集中了资金和权力，这对主流的采用构成了一个有意义的障碍。由于Pi的核心团队进行了研究，试图了解人们为什么不愿意进入加密货币领域。人们一直认为投资/采矿的风险是进入的主要障碍。

解决方案：在移动电话上启用Pi挖掘

在确定了这些关键的采用障碍之后，Pi核心团队开始寻找一种方法，允许日常用户挖掘（或通过验证分布式交易记录上的交易而获得加密货币奖励）。作为更新，维护分布式交易记录的一个主要挑战是确保对该开放记录的更新不存在欺诈。虽然比特币更新记录的过程已经被证明（燃烧能量/金钱来证明其可靠性），但它并不是很好的用户（或行星！）友好的。对于Pi，我们引入了使用一致性算法的额外设计要求，该算法也将非常友好，并且理想地能够在个人计算机和移动电话上进行挖掘。

在比较现有的一致性算法（将事务记录到分布式账本中的过程）时，Stellar一致性协议成为支持用户友好的移动优先挖掘的主要候选协议。恒星共识协议（SCP）由斯坦福大学计算机科学教授David Mazières设计，他也是恒星发展基金会的首席科学家。SCP使用一种称为联邦拜占庭协议（Federated Byzantine Agreements）的新机制来确保对分布式账本的更新是准确和可信的。SCP还通过自2015年以来一直运作的恒星区块链在实践中部署。

共识算法简介

在开始介绍Pi共识算法之前，先简单解释一下共识算法对区块链的作用，以及当今区块链协议通常使用的共识算法类型，例如比特币和SCP。为了清楚起见，本节以过于简单的方式明确地编写，并不完整。要获得更高的精度，请参阅下面的SCP适配部分，并阅读恒星共识协议文件。

区块链是一个容错的分布式系统，其目的是对交易块的列表进行完全排序。容错分布式系统是计算机科学中一个研究了几十年的领域。它们之所以被称为分布式系统，是因为它们没有集中的服务器，而是由分散的计算机列表（称为节点或对等点）组成，这些计算机需要就块的内容和总顺序达成共识。它们也被称为容错，因为它们可以容忍一定程度的故障节点进入系统（例如，多达33%的节点可能出现故障，整个系统继续正常运行）。

一致性算法有两大类：一类是选择一个节点作为产生下一个块的领队，另一类是没有明确领队但所有节点通过相互发送计算机消息来交换投票后对下一个块达成一致的算法。（严格地说，最后一句话包含了许多不准确之处，但它有助于我们解释大致的笔划。）

比特币使用第一种共识算法：所有比特币节点在解决密码难题时相互竞争。因为解是随机找到的，所以首先找到解的节点，碰巧被选为产生下一个块的回合的领导者。这种算法被称为“工作证明”，会导致大量的能量消耗。

恒星一致性协议简介

Pi使用其他类型的一致性算法，并基于Stellar一致性协议（SCP）和一个称为联邦拜占庭协议（FBA）的算法。这样的算法没有能量浪费，但它们需要交换许多网络消息，以便节点就下一个块应该是什么达成“共识”。每个节点可以根据加密签名和事务历史独立地确定事务是否有效，例如进行转换的权限和双重开销。然而，要使计算机网络就要在一个块中记录哪些事务以及这些事务和块的顺序达成一致，它们需要相互传递信息，并进行多轮投票才能达成共识。直观地说，来自网络中不同计算机的关于哪个块是下一个块的消息如下：“我建议我们都投票给块A作为下一个块”；“我投票给块A作为下一个块”；“我确认我信任的大多数节点也投票给块A”，共识算法可以从中该节点得出“A是下一个块；除了A作为下一个块之外，不可能有其他块”；尽管上面的投票步骤看起来很多，但互联网速度足够快，而且这些消息很轻，因此这种共识算法比比特币的工作证明更轻。这种算法的一个主要代表是拜占庭容错（BFT）。目前，一些顶级区块链基于BFT的变体，如NEO和Ripple。

对BFT的一个主要批评是它有一个集中点：由于涉及投票，参与投票“quorum”的节点集在开始时由系统创建者集中确定。FBA的贡献在于，每个节点设置自己的“仲裁片”，而不是有一个集中确定的仲裁，从而形成不同的仲裁。新的节点可以以分散的方式加入网络：它们声明它们信任的节点，并说服其他节点信任它们，但它们不必说服任何中心机构。

SCP是FBA的一个实例。SCP节点不是像比特币的工作证明一致性算法那样消耗能量，而是通过保证网络中的其他节点是可信的来保护共享记录。网络中的每个节点都构建一个仲裁片，由网络中它们认为可信的其他节点组成。quorum是基于其成员仲裁片形成的，验证器仅在其quorum中的一部分节点也接受事务时才会接受新事务。当网络上的验证器构建它们的quorum时，这些quorum帮助节点在保证安全的前提下就事务达成共识。你可以通过观看这段简短的7分钟解释视频或查看SCP的技术摘要来了解更多关于恒星共识协议的信息。

Pi对恒星一致性协议（SCP）的适应性

Pi的一致性算法构建在SCP之上。SCP已经过正式验证[Mazieres 2015]，目前正在恒星网络中实施。与主要由公司和机构（如IBM）组成的恒星网络不同，Pi打算允许个人设备在协议层面上做出贡献并获得奖励，包括手机、笔记本电脑和计算机。下面介绍Pi如何将SCP应用于允许个人进行挖掘。

作为Pi挖掘者，Pi用户可以扮演四个角色。即：

1、开拓者。一个Pi移动应用程序的用户，他只是每天确认自己不是“机器人”。此用户在每次登录应用程序时都验证其存在。他们还可以打开应用程序请求交易（例如，向另一个先锋支付Pi）

2、贡献者。Pi移动应用程序的用户，通过提供他或她所认识和信任的先驱的列表作出贡献。总而言之，Pi贡献者将构建一个全局信任图。

3、大使。Pi移动应用程序的用户，正在将其他用户引入Pi网络。

4、节点。一个用户，他是一个先锋，一个使用Pi移动应用程序的贡献者，并且还在他们的台式机或笔记本电脑上运行Pi节点软件。Pi节点软件是运行核心SCP算法的软件，它考虑了贡献者提供的信任图信息。

用户可以扮演以上角色中的多个。所有角色都是必要的，因此只要他们在当天参与和贡献，所有角色每天都会得到新的Pi奖励。在“miner”这个松散的定义中，这四个角色都被认为是Pi miners，即接收新币作为捐款奖励的用户。我们对“挖掘”的定义比传统意义上的执行工作证明一致性算法（如比特币或以太坊）更为宽泛。

首先，我们需要强调的是，Pi节点软件还没有发布。因此，本节更多地是作为建筑设计和征求技术界意见的请求提供的。该软件将是完全开放源码的，它也将在很大程度上依赖Starlar core，这也是开放源码软件，可在这里获得。这意味着社区中的任何人都可以阅读、评论和提出改进建议。下面是Pi对SCP的提议更改，以启用单个设备的挖掘。

节点

为了可读性，我们将正确连接的节点定义为SCP论文所指的完整节点。此外，为了可读性，我们定义主Pi网络为Pi网络中所有完整节点的集合。每个节点的主要任务配置为正确连接到主Pi网络。直观地说，错误地连接到主网络的节点类似于没有连接到主比特币网络的比特币节点。

在SCP的术语中，要使一个节点正确连接，意味着这个节点必须选择一个“仲裁片”，以便包括这个节点的所有结果quorum都与现有网络的quorum相交。更准确地说，如果N+1个节点（v1，v2，…，vn）的结果系统N’享受仲裁交叉，则节点vn+1正确地连接到N个已正确连接的节点（v1，v2，…，vn）的主网络N’上。换言之，如果N’的任意两个群共享一个节点，则N’享有仲裁交集。–也就是说，对于所有的U1和U2，U1∩U2≠∏。

Pi对现有的星共识部署的主要贡献是，它引入了Pi贡献者提供的信任图的概念，作为Pi节点在设置连接到主Pi网络的配置时可以使用的信息。

当选择它们的仲裁片时，这些节点必须考虑贡献者提供的信任图，包括它们自己的安全圈。为了辅助决策，我们打算提供辅助图分析软件，以帮助运行节点的用户尽可能做出明智的决策。该软件的每日输出将包括：

1、按与信任图中当前节点的距离排序的节点的排序列表；基于信任图中节点的pagerank分析的节点的排序列表

2、社区以任何方式报告故障的节点列表寻求加入网络的新节点列表

3、网站上关于关键字“行为不端的Pi节点”和其他相关关键字的最新文章列表；组成Pi网络的节点的可视化表示，类似于StellarBeat Quorum monitor中显示的内容[源代码]

4、类似于quorum explorer.com[源代码]的仲裁资源管理器

5、一种模拟工具，如StellarBeat仲裁监视器中的工具，当当前节点的配置更改时，它显示了对该节点到Pi网络的连接的预期结果影响。

未来工作的一个有趣的研究问题是开发算法，可以考虑信任图，并建议每个节点一个最佳配置，甚至自动设置该配置。在Pi网络的第一次部署中，虽然运行节点的用户可以随时更新其节点配置，但系统会提示他们每天确认其配置，并要求他们更新其配置（如果他们认为合适）。

移动应用用户

当先锋需要确认一个给定的事务已经执行（例如，他们已经收到Pi）时，他们会打开移动应用程序。此时，移动应用程序连接到一个或多个节点，以查询交易是否已记录在分类账上，并获取该块的最新块号和散列值。如果先锋也在运行一个节点，那么移动应用程序将连接到先锋自己的节点。如果Pioneer没有运行节点，则应用程序将连接到多个节点并交叉检查此信息。先驱者将能够选择他们希望应用程序连接到的节点。但是为了让大多数用户更简单，应用程序应该有一个合理的默认节点集，例如基于信任图的与用户最接近的一些节点，以及随机选择的pagerank较高的节点。我们要求您反馈如何选择移动先驱的默认节点集。

采矿奖励

SCP算法的一个优点是它比区块链更通用。它协调跨分布式节点系统的一致性。这意味着同一个核心算法不仅每隔几秒钟就被用于在新的块中记录新的事务，而且还可以用于周期性地运行更复杂的计算。例如，恒星网络每周一次使用它计算恒星网络的通货膨胀率，并按比例将新铸造的代币分配给所有的恒星硬币持有者（恒星的硬币被称为流明）。以类似的方式，Pi网络每天使用一次SCP来计算网络范围内所有积极参与某一天的Pi矿工（开拓者、贡献者、大使、节点）的新Pi分布。换句话说，Pi挖掘奖励每天只计算一次，而不是在区块链的每个区块上。

为了进行比较，比特币在每个区块上分配采矿奖励，并将所有奖励都给予有幸能够解决计算密集型随机任务的矿工。比特币奖励目前是每10分钟只奖励一名矿工12.5比特币（约4万美元）。这使得任何特定的矿工都极不可能获得奖励。作为一种解决方案，比特币矿商被组织在集中的采矿池中，这些采矿池都贡献了处理能力，增加了获得奖励的可能性，并最终按比例分享这些奖励。采矿池不仅是集中点，而且他们的运营商也得到削减，减少了对个体矿工的数量。在Pi中，不需要挖掘池，因为每天每个贡献者都会得到一个新Pi的精英分配。

交易费用

与比特币交易类似，在π网络中，费用是可选的。每个块中可以包含多少事务有一定的限制。当没有事务积压时，事务往往是免费的。但如果有更多的事务，则节点按费用排序，费用最高的事务位于顶部，并且只选择要包含在生成的块中的顶部事务。这使它成为一个开放的市场。实现：每天按比例在节点间分摊一次费用。在每个区块，每笔交易的费用都会转移到一个临时钱包中，在当天结束时从那里分发给当天的活跃矿工。这个钱包有一把不为人知的私钥。在所有节点的一致同意下，钱包内和钱包外的交易都是由协议本身强制进行的，同样，一致同意也会每天生成新的Pi。

局限性和未来工作

SCP作为Stellar网络的一部分已经被广泛测试了几年，在本文撰写之时，它是世界上第九大加密货币。这给了我们很大的信心。Pi项目的一个目标是将Pi网络中的节点数量扩展到大于恒星网络中的节点数量，以允许更多的日常用户参与核心共识算法。增加节点的数量，必然会增加它们之间必须交换的网络消息的数量。尽管这些消息比图片或youtube视频小得多，而且如今的互联网能够可靠地快速传输视频，但必要的消息数量会随着参与节点的数量而增加，这可能成为达成共识速度的瓶颈。这将最终减慢网络中记录新块和新事务的速率。值得庆幸的是，恒星目前比比特币快得多。目前，恒星被校准为每3到5秒产生一个新的数据块，每秒能够支持数千个事务。相比之下，比特币每10分钟就会产生一个新的区块。此外，由于比特币缺乏安全保障，比特币的区块链在极少数情况下可以在第一个小时内被覆盖。这意味着，比特币用户必须等待大约1小时，才能确保交易被视为最终交易。SCP保证了安全性，这意味着在3-5秒之后，就可以确定事务了。因此，即使存在潜在的可伸缩性瓶颈，Pi仍希望比比特币更快、甚至可能慢于Stellar，每秒处理的事务比比特币多，也可能比Stellar少。

而SCP的可扩展性仍然是一个开放性的研究问题。有多种有希望的方法可以加快速度。一种可能的可伸缩性解决方案是bloXroute。BloXroute提出了一种区块链分销网络（BDN），该网络利用针对网络性能优化的服务器全球网络。虽然每个BDN由一个组织集中控制，但它们提供了一个可证明的中立消息传递加速。一、 由于消息是加密的，BDNs只能公平地服务于所有节点而不受歧视。这意味着BDN不知道消息从哪里来，到哪里去，或者消息内部是什么。这样一来，Pi节点可以有两条消息传递路径：一条快速的直通BDN，大部分时间都是可靠的；另一条是它原来的完全分散可靠但速度较慢的对等消息传递接口。这种想法的直觉与缓存有着模糊的相似之处：缓存是一个计算机能够非常快速地访问数据、加快平均计算速度的地方，但它并不能保证总是拥有每一条所需的信息。当缓存未命中时，计算机将减慢速度，但不会发生灾难性的情况。另一个解决方案是在开放的对等网络中使用多播消息的安全确认[Nicolasi和Mazieres 2004]，以加快对等网络之间的消息传播。

Pi经济模型：平衡稀缺性和获取性

第一代经济模式的利弊

比特币最令人印象深刻的创新之一是它将分布式系统与经济博弈理论结合起来。

赞成的意见

固定供给

比特币的经济模式很简单。只有2100万比特币存在。这个号码是用代码设置的。由于全球75亿人口中只有2100万人流通，比特币的流通量不足。这种稀缺性是比特币价值的最重要驱动力之一。

减少区块奖励

下图所示的比特币发行计划进一步强化了这种稀缺感。比特币区块开采奖励每210000个区块（大约每4年）减半。在早期，比特币区块奖励为50个硬币。现在，奖励是12.5，到2020年5月将进一步减少到6.25金币。比特币发行率的下降意味着，即使人们对比特币的认识不断提高，但真正挖掘比特币的机会也越来越少。

欺骗

倒置意味着不均匀

比特币的反向发行模式（一开始收入越少的人越多，而现在收入越少的人越多）是造成其分布不均的主要原因之一。由于有这么多比特币掌握在一些早期采用者手中，新的矿商正在“燃烧”更多的能源来换取更少的比特币。

囤积阻碍了作为交换媒介的使用

尽管比特币是作为“点对点电子现金”系统发布的，但比特币的相对稀缺性阻碍了比特币作为媒介交换的目标。比特币的稀缺性导致它被视为一种“数字黄金”或价值的数字存储。这种看法的结果是，许多比特币持有者不愿意将比特币用于日常开支。

Pi经济模型

另一方面，圆周率试图在为圆周率创造稀缺感之间取得平衡，同时仍然确保大量的圆周率不会累积到极少数的手中。我们希望确保我们的用户在为网络做出贡献时获得更多的Pi。Pi的目标是建立一个经济模型，该模型足够复杂，能够实现和平衡这些优先事项，同时保持足够直观，供人们使用。

Pi经济模型设计要求：

1、简单：建立一个直观透明的模型

2、公平分配：让世界人口中的一个关键群体有机会获得个人所得税

3、稀缺性：创造一种稀缺感来维持圆周率的价格

4、精英收入：奖励为建立和维持网络作出的贡献

Pi-代币供应

代币排放政策

1、总最大供应量=M+R+D

M=采矿奖励总额

R=推荐奖励总额

D=开发人员奖励总额

2、M=∫f（P）dx其中f是对数递减函数

P=人口数量（例如，第一人加入，第二人加入等）

3、R=R*M

r=推荐率（总推荐率为50%，或推荐人和裁判均为25%）

4、D=t*（M+R）

5、t=开发商奖励率（25%）

M-采矿供应量（基于每人铸造的固定采矿供应量）

与比特币为全球人口创造了一个固定的硬币供应量不同，π为每个加入网络的人创造了一个固定的π供应量，直到第一个1亿参与者。换言之，对于加入Pi网络的每个人，都预先生成了固定数量的Pi。然后，根据该成员的参与程度和对网络安全的贡献，在该成员的整个生命周期内释放该供应。在成员的生命周期中，这种供给是通过类似比特币的指数递减函数释放的。

R-推荐供应（基于每人获得的固定推荐奖励和共享的b/w推荐人和推荐人）

为了使一种货币有价值，它必须广泛发行。为了激励这一目标，该协议还生成一个固定数量的Pi，作为推荐人和推荐人（或父母和子女）的推荐奖金。当双方都在积极开采时，双方可以在其生命周期内开采该共享池。推荐人和裁判都可以利用这个池，以避免剥削模型，其中推荐人可以“猎物”他们的裁判。推荐奖金是一种网络级别的激励措施，可以促进Pi网络的发展，同时也可以激励会员参与积极保护网络。

D-开发商奖励供应（额外的Pi铸造以支持正在进行的开发）

Pi将为其正在进行的开发提供资金，并在每一枚用于采矿和转介的硬币旁边铸造“开发商奖励”。传统上，加密货币协议已经创造了一个固定数量的供应量，并立即存入国库。由于Pi的总供应量取决于网络中的成员数量，因此随着网络规模的扩大，Pi逐渐获得其开发者的报酬。Pi开发者奖励的逐步形成是为了将Pi贡献者的奖励与网络的整体健康状况相结合。

f是对数递减函数-早期成员赚得更多

尽管π试图避免财富的极端集中，但该网络也试图用π中相对较大的份额来奖励早期成员及其贡献。当Pi等网络处于早期阶段时，它们往往为参与者提供较低的效用。例如，想象一下拥有世界上第一部电话。这将是一个伟大的技术创新，但不是非常有用。然而，随着越来越多的人获得电话，每个电话持有者从网络中获得更多的效用。为了奖励早来网络的人，π的个人挖掘奖励和推荐奖励随着网络人数的减少而减少。换句话说，Pi网络中的每个“时隙”都保留了一定数量的Pi。

效用：将我们的在线时间集中起来并将其货币化

今天，每个人都坐在未开发资源的宝库里。我们每个人每天都花几个小时打电话。在我们的手机上，我们的每一个观点、帖子或点击都为大公司创造了非凡的利润。在Pi，我们相信人们有权从他们的资源中获取创造的价值。

我们都知道我们可以一起做比单独做更多的事。在今天的网络上，像谷歌、亚马逊、Facebook这样的大公司对个人消费者有着巨大的影响力。因此，他们能够在网络上捕捉到个人消费者创造的价值狮子座。圆周率通过允许其成员集合他们的集体资源，以便他们能够分享他们创造的价值，来平衡竞争环境。

下图是Pi堆栈，在这里我们看到了帮助我们的成员获取价值的特别有希望的机会。下面，我们将更详细地介绍每一个领域。

引入Pi堆栈-释放未充分利用的资源

Pi Ledger和共享信任图-在Web上扩展信任

互联网上最大的挑战之一是知道谁值得信任。今天，我们依靠亚马逊、易趣、Yelp等服务商的评级系统来了解我们可以在互联网上与谁交易。尽管事实上，我们，客户，做了艰苦的工作，评级和审查我们的同行，这些互联网中介捕捉狮子座的价值创造这项工作。

上面描述的Pi的一致性算法创建了一个本机信任层，它在没有中介的情况下扩展web上的信任。虽然只有一个个人的安全圈的价值很小，但我们的个人安全圈的总和构建了一个全球“信任图”，帮助人们了解Pi网络上谁可以被信任。Pi网络的全局信任图将促进陌生人之间原本不可能进行的交易。反过来，Pi的本币允许为网络安全做出贡献的每个人分享他们帮助创造的价值。

Pi的注意力市场-以未利用的注意力和时间交换

Pi允许其成员集中他们的集体注意力，创造一个比任何个人的注意力都更有价值的注意力市场。在这一层上构建的第一个应用程序将是一个稀缺的社交媒体频道，目前托管在应用程序的主屏幕上。你可以把这一稀缺的社交媒体频道想象成Instagram，一次只能发布一个全球帖子。先驱者可以通过分享内容（如文本、图片、视频）或提问来吸引网络其他成员的注意力，以期挖掘社区的集体智慧。在π网络上，每个人都有机会成为一个有影响力的人，或者挖掘人群的智慧。到目前为止，Pi的核心团队一直在利用这个渠道调查社区对Pi设计选择的意见（例如，社区对Pi标志的设计和颜色进行了投票）。我们收到了来自社区对项目的许多有价值的回应和反馈。未来一个可能的方向是开放注意力市场，让任何先锋都可以使用Pi发布自己的内容，同时扩大Pi网络上托管的频道数量。

除了与同龄人交换注意力之外，先驱者还可以选择与寻求关注的公司进行交换。美国人平均每天看到4000到10000条广告。公司为吸引我们的注意力而奋斗，并为此付出了巨大的代价。但我们，客户，从这些交易中得不到任何价值。在π的注意力市场，公司寻求达到先驱将不得不补偿他们的观众在π。圆周率的广告市场将是严格的选择只，并将提供一个机会，开拓者货币化他们最大的未开发资源之一：他们的注意力。

Pi的易货市场-建立你的个人虚拟店面

除了对Pi网络提供信任和关注之外，我们还希望先锋能够在未来贡献他们独特的技能和服务。Pi的移动应用程序还将作为销售点，Pi的成员可以通过“虚拟店面”向Pi网络的其他成员提供他们尚未开发的商品和服务。例如，一个成员在他们的公寓里提供一个未充分利用的房间出租给Pi网络上的其他成员。除了实物资产，Pi网络的成员还可以通过虚拟店面提供技能和服务。例如，Pi网络的成员可以在Pi市场上提供他们的编程或设计技能。随着时间的推移，Pi的价值将得到一篮子不断增长的商品和服务的支撑。

Pi的分散应用商店——降低了创作者的进入门槛

Pi网络的共享货币、信任图和市场将成为更广泛的分散应用生态系统的土壤。今天，任何想要启动应用程序的人都需要从头开始启动其技术基础设施和社区。Pi的分散应用程序存储将允许Dapp开发人员利用Pi的现有基础设施以及社区和用户的共享资源。企业家和开发者可以向社区提出新的dapp，请求访问网络的共享资源。Pi还将构建具有某种程度互操作性的dapp，以便dapp能够引用其他分散应用程序中的数据、资产和流程。

治理-为人民服务的加密货币

挑战与第一代治理模式

信任是任何成功的货币体系的基础。产生信任的最重要因素之一是治理，即随着时间的推移对协议进行更改的过程。尽管治理很重要，但它往往是密码经济系统中最容易被忽视的方面之一。

比特币（Bitcoin）等第一代网络在很大程度上避免了正式（或“链上”）的治理机制，而采用了非正式（或“链下”）机制，这种机制是角色和激励设计的结合。从大多数指标来看，比特币的治理机制相当成功，使得该协议自诞生以来在规模和价值上都有了显著的增长。然而，也存在一些挑战。比特币的经济集中导致了政治权力的集中。其结果是，每天人们都可能陷入比特币大持有者之间的破坏性战斗之中。这一挑战的最新例子之一是比特币和比特币现金之间正在进行的战斗。这些内战可能会在区块链的某个分支处或某个分支处结束。对于代币持有者来说，硬叉子会导致通胀，并可能威胁到他们持有的代币的价值。

Pi的治理模型-一个两阶段计划

在一篇挑战链上治理优点的文章中，以太坊核心开发者之一弗拉德•赞菲尔（Vlad Zamfir）认为，区块链治理“不是一个抽象的设计问题。这是一个应用性的社会问题。”弗拉德的一个关键点是，很难“事先”或在观察到某一特定政治制度所带来的特殊挑战之前设计治理体系。一个历史性的例子是美国的建立。美国的第一个民主实验，联邦条款，在八年的实验后失败了。当时，美国的开国元勋们能够借鉴《联邦法》的经验来制定宪法，这是一个更加成功的实验。

为了建立一个持久的治理模式，Pi将采用两阶段计划。

临时治理模式（<500万成员）

在网络达到500万成员的临界数量之前，Pi将在临时治理模式下运作。这个模型将与比特币和以太坊等协议目前采用的“链外”治理模型最为相似，Pi的核心团队在指导协议的开发方面发挥着重要作用。然而，Pi的核心团队仍将严重依赖社区的投入。π移动应用程序本身就是π的核心团队一直在征求社区的意见并与先驱者接触的地方。Pi包含社区评论和建议，这是由Pi的登录页、faq和白皮书的open for comments特性实现的。每当人们在Pi的网站上浏览这些材料时，他们都可以在某个特定的部分发表评论，提出问题并提出建议。Pi的核心团队组织的离线先锋会议也将成为社区投入的重要渠道。

此外，Pi的核心团队将开发更正式的治理机制。一个潜在的治理体系是流动民主。在流动民主中，每个先驱者都有能力直接就一个问题投票，或者将他们的投票权委托给网络的另一个成员。流动民主将使Pi的社区成员既广泛又高效。

Pi的“制宪会议”（超过500万名成员）

一旦达到500万名成员，将根据以前对Pi网络的贡献成立一个临时委员会。该委员会将负责向更广泛的社区征求和提出建议。它还将组织一系列的线上和线下对话，在这些对话中，π的成员将能够衡量π的长期宪法。鉴于Pi的全球用户群，Pi网络将在世界各地的多个位置执行这些约定，以确保可访问性。除了亲自主持会议外，Pi还将使用其移动应用程序作为平台，允许Pi的成员远程参与进程。无论是面对面还是在线，Pi的社区成员都将有能力参与到Pi的长期治理结构中。

路线图/部署计划

第1阶段-设计、分发、信任图引导。

Pi服务器作为一个水龙头运行，模拟分散式系统的行为，因为它将在其运行后立即工作。在这一阶段，用户体验和行为的改善是可能的，而且与主网的稳定阶段相比相对容易实现。所有的硬币铸造用户将迁移到直播网一旦推出。换言之，livenet将在其genesis中预先生成所有在第1阶段生成的账户持有人余额，并继续像当前系统一样运行，但完全分散。在这一阶段，圆周率没有在交易所上市，不可能用任何其他货币“买入”圆周率。

第2阶段-测试网

在我们启动主网之前，节点软件将部署在测试网上。测试网将使用与主网相同的精确信任图，但在测试Pi币上。Pi核心团队将在测试网络上托管多个节点，但将鼓励更多的先驱在测试网络上启动自己的节点。实际上，为了让任何节点加入主网络，建议它们从testnet开始。测试网络将在第一阶段与Pi模拟器并行运行，并定期（例如每天）比较两个系统的结果，以捕捉测试网络的间隙和遗漏，这将允许Pi开发人员提出和实现修复。在两个系统完全并发运行之后，testnet将达到其结果与仿真器一致的状态。当社区感觉到它已经准备好时，Pi将迁移到下一个阶段。

第3阶段-主网

当社区觉得软件已经准备好生产，并且已经在testnet上进行了彻底的测试时，Pi网络的官方主网就会启动。一个重要的细节是，在向主网过渡的过程中，只有经过验证属于不同真实个人的帐户才会被接受。之后，一期的水龙头和Pi网络仿真器将关闭，系统将永远独立运行。未来对协议的更新将由Pi开发者社区和Pi的核心团队提供，并由委员会提出。它们的实现和部署将依赖于节点更新挖掘软件，就像任何其他区块链一样。没有一个中央政府会控制货币，货币将完全分散。假用户或重复用户的余额将被丢弃。在这个阶段，圆周率可以与外汇挂钩，也可以与其他货币兑换。

附：Pi币白皮书英文原版

Introduction

Problem: Accessibility of 1st Gen Cryptocurrencies

Solution: Pi – Mining Goes Mobile

Pi Economic Model: Balancing Scarcity and Access

Utility: Monetizing untapped resources in p2p

Governance – Currency for and by the people

Roadmap / Deployment plan

Draft 1 on March 14, 2019

Preface

As the world becomes increasingly digital, cryptocurrency is a next natural step in the evolution of money. Pi is the first digital currency for everyday people, representing a major step forward in the adoption of cryptocurrency worldwide.

Our Mission: Build a cryptocurrency and smart contracts platform secured and operated by everyday people.

Our Vision: Build the world’s most inclusive peer-to-peer marketplace, fueled by Pi, the world’s most widely used cryptocurrency

DISCLAIMER for more advanced readers: Because Pi’s mission is to be inclusive as possible, we’re going to take this opportunity to introduce our blockchain newbies to the rabbit hole 🙂

Introduction: Why cryptocurrencies matter

Currently, our everyday financial transactions rely upon a trusted third party to maintain a record of transactions. For example, when you do a bank transaction, the banking system keeps a record & guarantees that the transaction is safe & reliable. Likewise, when Cindy transfers $5 to Steve using PayPal, PayPal maintains a central record of $5 dollars debited from Cindy’s account and $5 credited to Steve’s. Intermediaries like banks, PayPal, and other members of the current economic system play an important role in regulating the world’s financial transactions.

However, the role of these trusted intermediaries also has limitations:

Unfair value capture. These intermediaries amass billions of dollars in wealth creation (PayPal market cap is ~$130B), but pass virtually nothing onto their customers – the everyday people on the ground, whose money drives a meaningful proportion of the global economy. More and more people are falling behind.

Fees. Banks and companies charge large fees for facilitating transactions. These fees often disproportionately impact lower-income populations who have the fewest alternatives.

Censorship. If a particular trusted intermediary decides that you should not be able to move your money, it can place restrictions on the movement of your money.

Permissioned. The trusted intermediary serves as a gatekeeper who can arbitrarily prevent anybody from being part of the network.

Pseudonymous. At a time when the issue of privacy is gaining greater urgency, these powerful gatekeepers can accidentally disclose — or force you to disclose — more financial information about yourself than you may want.

Bitcoin’s “peer-to-peer electronic cash system,” launched in 2009 by an anonymous programmer (or group) Satoshi Nakamoto, was a watershed moment for the freedom of money. For the first time in history, people could securely exchange value, without requiring a third party or trusted intermediary. Paying in Bitcoin meant that people like Steve and Cindy could pay each other directly, bypassing institutional fees, obstructions and intrusions. Bitcoin was truly a currency without boundaries, powering and connecting a new global economy.

Introduction to Distributed Ledgers

Bitcoin achieved this historical feat by using a distributed record. While the current financial system relies on the traditional central record of truth, the Bitcoin record is maintained by a distributed community of “validators,” who access and update this public ledger. Imagine the Bitcoin protocol as a globally shared “Google Sheet” that contains a record of transactions, validated and maintained by this distributed community.

The breakthrough of Bitcoin (and general blockchain technology) is that, even though the record is maintained by a community, the technology enables them to always reach consensus on truthful transactions, insuring that cheaters cannot record false transactions or overtake the system. This technological advancement allows for the removal of the centralized intermediary, without compromising transactional financial security.

Benefits of distributed ledgers

In addition to decentralization, bitcoin, or cryptocurrencies in general, share a few nice properties that make money smarter and safer, although different cryptocurrencies may be stronger in some properties and weaker in others, based on different implementations of their protocols.  Cryptocurrencies are held in cryptographic wallets identified by a publicly accessible address, and is secured by a very strong privately held password, called the private key. This private key cryptographically signs transaction and is virtually impossible to create fraudulent signatures. This provides security and unseizability. Unlike traditional bank accounts that can be seized by government authorities, the cryptocurrency in your wallet can never be taken away by anyone without your private key. Cryptocurrencies are censorship resistant due to the decentralized nature because anyone can submit transactions to any computer in the network to get recorded and validated. Cryptocurrency transactions are immutable because each block of transactions represents a cryptographic proof (a hash) of all the previous blocks that existed before that. Once someone sends you money, they cannot steal back their payment to you (i.e., no bouncing checks in blockchain). Some of the cryptocurrencies can even support atomic transactions. “Smart contracts” built atop these cryptocurrencies do not merely rely on law for enforcement, but directly enforced through publicly auditable code, which make them trustless and can potentially get rid of middlemen in many businesses, e.g. Escrow for real estate.

Securing distributed ledgers (Mining)

One of challenges of maintaining a distributed record of transactions is security — specifically, how to have an open and editable ledger while preventing fraudulent activity. To address this challenge, Bitcoin introduced a novel process called Mining (using the consensus algorithm “Proof of Work”) to determine who is “trusted” to make updates to the shared record of transactions.

You can think of mining as a type of economic game that forces “Validators” to prove their merit when trying to add transactions to the record. To qualify, Validators must solve a series of complex computational puzzles. The Validator who solves the puzzle first is rewarded by being allowed to post the latest block of transactions. Posting the latest block of transactions allows Validators to “mine” a Block Reward – currently 12.5 bitcoin (or ~$40,000 at the time of writing).

This process is very secure, but it demands enormous computing power and energy consumption as users essentially “burn money” to solve the computational puzzle that earns them more Bitcoin. The burn-to-reward ratio is so punitive that it is always in Validators’ self-interest to post honest transactions to the Bitcoin record.

Problem: Centralization of power and money put 1st Generation Cryptocurrencies out of reach

In the early days of Bitcoin, when only a few people were working to validate transactions and mining the first blocks, anyone could earn 50 BTC by simply running Bitcoin mining software on their personal computer. As the currency began to gain in popularity, clever miners realized that they could earn more if they had more than one computer working to mine.

As Bitcoin continued to increase in value, entire companies began to spring up to mine. These companies developed specialized chips (“ASICs”) and constructed huge farms of servers using these ASIC chips to mine Bitcoin. The emergence of these enormous mining corporations, known drove the Bitcoin Gold Rush, making it very difficult for everyday people to contribute to the network and get rewarded. Their efforts also began consuming increasingly large amounts of computing energy, contributing to mounting environmental issues around the world.

The ease of mining Bitcoin and the subsequent rise of Bitcoin mining farms quickly produced a massive centralization of production power and wealth in Bitcoin’s network. To provide some context, 87% of all Bitcoins are now owned by 1% of their network, many of these coins were mined virtually free in their early days. As another example, Bitmain, one of Bitcoin’s biggest mining operations has earned billions in revenue and profits.

The centralization of power in Bitcoin’s network makes it very difficult and expensive for the average person. If you want to acquire Bitcoin, your easiest options are to:

Mine It Yourself. Just hook up the specialized hardware (here’s a rig on Amazon, if you’re interested!) and go to town. Just know that since you’ll be competing against massive server farms from across the world, consuming as much energy as the country of Switzerland, you won’t be able to mine much

Buy Bitcoin on an exchange. Today, you can buy Bitcoin at a unit price of $3,500 / coin at the time of writing (note: you can buy fractional amount of Bitcoin!) Of course, you would also be taking on substantial risk in doing so as the price of Bitcoin is quite volatile.

Bitcoin was the first to show how cryptocurrency could disrupt the current financial model, giving people the ability to make transactions without having a third party in the way. The increase in freedom, flexibility, and privacy continues to drive the inevitable march toward digital currencies as a new norm. Despite its benefits, Bitcoin’s (likely unintended) concentration of money and power present a meaningful barrier to mainstream adoption. As Pi’s core team has conducted research to try to understand why people are reluctant to enter the cryptocurrency space. People consistently cited the risk of investing/mining as a key barrier to entry.

Solution: Pi – Enabling mining on mobile phones

After identifying these key barriers to adoption, the Pi Core Team set out to find a way that would allow everyday people to mine (or earn cryptocurrency rewards for validating transactions on a distributed record of transactions). As a refresher, one of the major challenges that arises with maintaining a distributed record of transactions is ensuring that updates to this open record are not fraudulent. While Bitcoin’s process for updating its record is proven (burning energy / money to prove trustworthiness), it is not very user (or planet!) friendly. For Pi, we introduced the additional design requirement of employing a consensus algorithm that would also be extremely user friendly and ideally enable mining on personal computers and mobile phones.

In comparing existing consensus algorithms (the process that records transactions into a distributed ledger), the Stellar Consensus Protocol emerges as the leading candidate to enable user-friendly, mobile-first mining. Stellar Consensus Protocol (SCP) was architected by David Mazières a professor of Computer Science at Stanford who also serves as Chief Scientist at the Stellar Development Foundation. SCP uses a novel mechanism called Federated Byzantine Agreements to ensure that updates to a distributed ledger are accurate and trustworthy. SCP is also deployed in practice through the Stellar blockchain that has been operating since 2015.

A simplified introduction to consensus algorithms

Before jumping to introducing the Pi consensus algorithm, it helps to have a simple explanation on what a consensus algorithm does for a blockchain and the types of consensus algorithms that today’s blockchain protocols generally use, e.g. Bitcoin and SCP. This section is explicitly written in a oversimplified manner for the sake of clarity, and is not complete. For higher accuracy, see the section Adaptations to SCP below and read the stellar consensus protocol paper.

A blockchain is a fault-tolerant distributed system that aims to totally order a list of blocks of transactions. Fault-tolerant distributed systems is an area of computer science that has been studied for many decades. They are called distributed systems because they do not have a centralized server but instead they are composed of a decentralized list of computers (called nodes or peers) that need to come to a consensus as to what is the content and total ordering of blocks. They are also called fault-tolerant because they can tolerate a certain degree of faulty nodes into the system (e.g. up to 33% of nodes can be faulty and the overall system continues to operate normally).

There are two broad categories of consensus algorithms: The ones that elect a node as the leader who produces the next block, and the ones where there is no explicit leader but all nodes come to a consensus of what the next block is after exchanging votes by sending computer messages to each other. (Strictly speaking the last sentence contains multiple inaccuracies, but it helps us explain the broad strokes.)

Bitcoin uses the first type of consensus algorithm: All bitcoin nodes are competing against each other in solving a cryptographic puzzle. Because the solution is found randomly, essentially the node that finds the solution first, by chance, is elected the leader of the round who produces the next block. This algorithm is called “Proof of work” and results in a lot of energy consumption.

A simplified introduction to Stellar Consensus Protocol

Pi uses the other type of consensus algorithms and is based on the Stellar Consensus Protocol (SCP) and an algorithm called Federated Byzantine Agreement (FBA). Such algorithms don’t have energy waste but they require exchanging many network messages in order for the nodes to come to “consensus” on what the next block should be. Each node can independently determine if a transaction is valid or not, e.g. authority of making the transition and double spending, based on the cryptographic signature and the transaction history. However, for a network of computers to agree on which transactions to record in a block and the order of these transactions and blocks, they need to message each other and have multiple rounds of voting to come to consensus. Intuitively, such messages from different computers in the network about which block is the next would look like the following: “I propose we all vote for block A to be next”; “I vote for block A to be the next block”; “I confirm that the majority of the nodes I trust also voted for block A”, from which the consensus algorithm enables this node to conclude that “A is the next block; and there could be no block other than A as the next block”;  Even though the above voting steps seem a lot, the internet is adequately fast and these messages are lightweight, thus such consensus algorithms are more lightweight than Bitcoin’s proof of work. One major representative of such algorithms is called Byzantine Fault Tolerance (BFT). Several of the top blockchains today are based on variants of BFT, such as NEO and Ripple.

One major criticism of BFT is that it has a centralization point: because voting is involved, the set of nodes participating in the voting “quorum” are centrally determined by the creator of the system in its beginning. The contribution of FBA is that, instead of having one centrally determined quorum, each node sets their own “quorum slices”, which will in turn form different quorums. New nodes can join the network in a decentralized way: they declare the nodes that they trust and convince other nodes to trust them, but they don’t have to convince any central authority.

SCP is one instantiation of FBA. Instead of burning energy like in Bitcoin’s proof of work consensus algorithm, SCP nodes secure the shared record by vouching for other nodes in the network as trustworthy. Each node in the network builds a quorum slice, consisting of other nodes in the network that they deem to be trustworthy. Quorums are formed based on its members quorum slices, and a validator will only accept new transactions if and only if a proportion of nodes in their quorums will also accept the transaction. As validators across the network construct their quorums, these quorums help nodes to reach consensus about transactions with guarantee on security. You can learn more about the Stellar Consensus Protocol by watching this short, 7 min explanation video or checking out this technical summary of SCP.

Pi’s Adaptations to Stellar Consensus Protocol (SCP)

Pi’s consensus algorithm builds atop SCP.  SCP has been formally proven [Mazieres 2015] and is currently implemented within the Stellar Network. Unlike Stellar Network consisting mostly of companies and institutions (e.g., IBM) as nodes, Pi intends to allow devices of individuals to contribute on the protocol level and get rewarded, including mobile phones, laptops and computers. Below is an introduction on how Pi applies SCP to enabling mining by individuals.

There are four roles Pi users can play, as Pi miners. Namely:

Pioneer. A user of the Pi mobile app who is simply confirming that they are not a “robot” on a daily basis. This user validates their presence every time they sign in to the app. They can also open the app to request transactions (e.g. make a payment in Pi to another Pioneer)

Contributor. A user of the Pi mobile app who is contributing by providing a list of pioneers he or she knows and trusts. In aggregate, Pi contributors will build a global trust graph.

Ambassador. A user of the Pi mobile app who is introducing other users into Pi network.

Node. A user who is a pioneer, a contributor using the Pi mobile app, and is also running the Pi node software on their desktop or laptop computer. The Pi node software is the software that runs the core SCP algorithm, taking into account the trust graph information provided by the Contributors.

A user can play more than one of the above roles. All roles are necessary, thus all roles are rewarded with newly minted Pi on a daily basis as long as they participated and contributed during that given day. In the loose definition of a “miner” being a user who receives newly minted currency as a reward for contributions, all four roles are considered to be Pi miners. We define“mining” more broadly than its traditional meaning equated to executing proof of work consensus algorithm as in Bitcoin or Ethereum.

First of all, we need to emphasize that the Pi Node software has not been released yet. So this section is offered more as an architectural design and as a request to solicit comments from the technical community. This software will be fully open source and it will also heavily depend on stellar-core which is also open source software, available here. This means that anyone in the community will be able to read, comment and propose improvements on it. Below are the Pi proposed changes to SCP to enable mining by individual devices.

Nodes

For readability, we define as a correctly connected node to be what the SCP paper refers to as an intact node. Also, for readability, we define as the main Pi network to be the set of all intact nodes in the Pi network. The main task of each Node is to be configured to be correctly connected to the main Pi network. Intuitively, a node being incorrectly connected to the main network is similar to a Bitcoin node not being connected to the main bitcoin network.

In SCP’s terms, for a node to get correctly connected means that this node must chose a “quorum slice” such that all resulting quorums that include this node intersect with the existing network’s quorums. More precisely, a node vn+1 is correctly connected to a main network N of n already correctly connected nodes (v1, v2, …, vn) if the resulting system N’ of n+1 nodes (v1, v2, …, vn+1) enjoys quorum intersection. In other words, N’ enjoys quorum intersection iff any two of its quorums share a node. — i.e., for all quorums U1 and U2, U1∩U2 ≠ ∅.

The main contribution of Pi over the existing Stellar consensus deployment is that it introduces the concept of a trust graph provided by the Pi Contributors as information that can be used by the Pi nodes when they are setting up their configurations to connect to the main Pi network.

When picking their quorum slices, these Nodes must take into consideration the trust graph provided by the Contributors, including their own security circle. To assist in this decision, we intend to provide auxiliary graph analysis software to assist users running Nodes to make as informed decisions as possible. This software’s daily output will include:

a ranked list of nodes ordered by their distance from the current node in the trust graph; a ranked list of nodes based a pagerank analysis of nodes in the trust graph

a list of nodes reported by the community as faulty in any way a list of new nodes seeking to join the network

a list of most recent articles from the web on the keyword “misbehaving Pi nodes” and other related keywords; a visual representation of Nodes comprising the Pi network similar to what is shown in StellarBeat Quorum monitor [source code]

a quorum explorer similar to QuorumExplorer.com [source code]

a simulation tool like the one in StellarBeat Quorum monitor that shows the expected resulting impacts to this nodes’ connectivity to the Pi network when the current node’s configuration changes.

An interesting research problem for future work is to develop algorithms that can take into consideration the trust graph and suggest each node an optimal configuration, or even set that configuration automatically. On the first deployment of the Pi Network, while users running Nodes can update their Node configuration at any time, they will be prompted to confirm their configurations daily and asked to update them if they see fit.

Mobile app users

When a Pioneer needs to confirm that a given transaction has been executed (e.g. that they have received Pi) they open the mobile app. At that point, the mobile app connects to one or more Nodes to inquire if the transaction has been recorded on the ledger and also to get the most recent block number and hash value of that block. If that Pioneer is also running a Node the mobile app connects to that Pioneer’s own node. If the Pioneer is not running a node, then the app connects to multiple nodes and to cross check this information. Pioneers will have the ability select which nodes they want their apps to connect to. But to make it simple for most users, the app should have a reasonable default set of nodes, e.g. a number of nodes closest to the user based on the trust graph, along with a random selection of nodes high in pagerank. We ask for your feedback on how the default set of nodes for mobile Pioneers should be selected.

Mining rewards

A beautiful property of the SCP algorithm is that it is more generic than a blockchain. It coordinates consensus across a distributed system of Nodes. This means that the same core algorithm is not only used every few seconds to record new transactions in new blocks, but also it can be used to periodically run more complex computations. For example, once a week, the stellar network is using it to compute inflation on the stellar network and allocate the newly minted tokens proportionally to all stellar coin holders (Stellar’s coin is called lumens). In a similar manner, the Pi network employs SCP once a day to compute the network-wide new Pi distribution across all Pi miners (pioneers, contributors, ambassadors, nodes) who actively participated in any given day. In other words, Pi mining rewards are computed only once daily and not on every block of the blockchain.

For comparison Bitcoin allocates mining rewards on every block and it give all of the reward to the miner who was lucky enough to be able to solve a computationally intensive randomized task. This reward in Bitcoin currently 12.5 Bitcoin (~$40K) is given to only one miner every 10 minutes. This makes it extremely unlikely for any given miner to ever get rewards. As a solution to that, bitcoin miners are getting organized in centralized mining pools, which all contribute processing power, increasing the likelihood of getting rewards, and eventually sharing proportionally those rewards. Mining pools are not only points of centralization, but also their operators get cuts reducing the amount going to individual miners.  In Pi, there is no need for mining pools, since once a day everyone who contributed get a meritocratic distribution of new Pi.

Transaction fees

Similar to Bitcoin transactions, fees are optional in the Pi network. Each block has a certain limit of how many transactions can be included in it. When there is no backlog of transactions, transactions tend to be free. But if there are more transactions, nodes order them by fee, with highest-fee-transactions at the top and pick only the top transactions to be included in the produced blocks. This makes it an open market. Implementation: Fees are proportionally split among Nodes once a day. On every block, the fee of each transaction is transferred into a temporary wallet from where in the end of the day it is distributed to the active miners of the day. This wallet has an unknown private key. Transactions in and out of that wallet are forced by the protocol itself under the consensus of all nodes in the same way the consensus also mints new Pi every day.

Limitations and future work

SCP has been extensively tested for several years as part of the Stellar Network, which at the time of this writing is the ninth largest cryptocurrency in the world. This gives us a quite large degree of confidence in it. One ambition of the Pi project is to scale the number of nodes in the Pi network to be larger than the number of nodes in the Stellar network to allow more everyday users to participate in the core consensus algorithm. Increasing the number of nodes, will inevitably increase the number of network messages that must be exchanged between them. Even though these messages are much smaller than an image or a youtube video, and the Internet today can reliably transfer videos quickly, the number of messages necessary increases with the number of participating nodes, which can become bottleneck to the speed of reaching consensus. This will ultimately slow down the rate, at which new blocks and new transactions are recorded in the network. Thankfully, Stellar is currently much faster than Bitcoin. At the moment, Stellar is calibrated to produce a new block every 3 to 5 seconds, being able to support thousands of transactions per second. By comparison, Bitcoin produces a new block every 10 minutes. Moreover, due to Bitcoin’s lack in the safety guarantee, Bitcoin’s blockchain in rare occasions can be overwritten within the first hour. This means that a user of Bitcoin must wait about 1 hour before they can be sure that a transaction is considered final. SCP guarantees safety, which means after 3-5 seconds one is certain about a transaction. So even with the potential scalability bottleneck,  Pi expects to achieve transaction finality faster than Bitcoin and possibly slower than Stellar, and process more transactions per second than Bitcoin and possibly fewer than Stellar.

While scalability of SCP is still an open research problem. There are multiple promising ways one could speed things up. One possible scalability solution is bloXroute. BloXroute proposes a blockchain distribution network (BDN) that utilizes a global network of servers optimized for network performance. While each BDN is centrally controlled by one organization, they offer a provably neutral message passing acceleration. I.e. BDNs can only serve all nodes fairly without discrimination as messages are encrypted. This means the BDN does not know where messages come from, where they go, or what is inside. This way Pi nodes can have two message passing routes: A fast one through BDN, which is expected to be reliable most of the time, and its original peer-to-peer message passing interface that is fully decentralized and reliable but is slower. The intuition of this idea is vaguely similar to caching: The cache is place where a computer can access data very quickly, speeding the average computation, but it is not guaranteed to always have every needed piece of information. When the cache misses, the computer is slowed down but nothing catastrophic happens. Another solution can be using secure acknowledgment of multicast messages in open Peer-to-Peer networks [Nicolosi and Mazieres 2004] to speed up message propagation among peers.

Pi Economic Model: Balancing Scarcity and Access

Pros and cons of 1st Generation Economic Models

One of Bitcoin’s most impressive innovations is its marriage of distributed systems with economic game theory.

Pros

Fixed Supply

Bitcoin’s economic model is simple. There will only ever be 21 million Bitcoin in existence. This number is set in code. With only 21M to circulate among 7.5B people around the world, there is not enough Bitcoin to go around. This scarcity is one of most important drivers of Bitcoin’s value.

Decreasing Block Reward

Bitcoin’ distribution scheme, pictured below, further enforces this sense of scarcity. The Bitcoin block mining reward halves every 210,000 blocks (approximately every ~4 years.) In its early days, the Bitcoin block reward was 50 coins. Now, the reward is 12.5, and will further decrease to 6.25 coins in May 2020. Bitcoin’s decreasing rate of distribution means that, even as awareness of the currency grows, there is less to actually mine.

Cons

Inverted Means Uneven

Bitcoin’s inverted distribution model (less people earning more in the beginning, and more people earn less today) is one of the primary contributors to its uneven distribution. With so much Bitcoin in the hands of a few early adopters, new miners are “burning” more energy for less bitcoin.

Hoarding Inhibits Use as a Medium of Exchange

Although Bitcoin was released as a “peer to peer electronic cash” system, the relative scarcity of Bitcoin has impeded Bitcoin’s goal of serving as a medium exchange. Bitcoin’s scarcity has led to its perception as a form of “digital gold” or a digital store of value. The result of this perception is that many Bitcoin holders are unwilling to spend Bitcoin on day-to-day expenses.

The Pi Economic Model

Pi, on the other hand, seeks to strike a balance between creating a sense of scarcity for Pi, while still ensuring that a large amount does not accumulate into a very small number of hands. We want to make sure our users earn more Pi as they make contributions to the network. Pi’s goal is to build an economic model that is sophisticated enough to achieve and balance these priorities while remaining intuitive enough for people to use.

Pi’s economic model design requirements:

Simple: Build an intuitive and transparent model

Fair distribution: Give a critical mass of the world’s population access to Pi

Scarcity: Create a sense of scarcity to sustain Pi’s price over time

Meritocratic earning: Reward contributions to build and sustain the network

Pi – Token Supply

Token Emission Policy

Total Max Supply = M + R + D

M = total mining rewards

R = total referral rewards

D = total developer rewards

M = ∫ f(P) dx where f is a logarithmically declining function

P = Population number (e.g., 1st person to join, 2nd person to join, etc.)

R = r * M

r = referral rate (50% total or 25% for both referrer and referee)

D = t * (M + R)

t = developer reward rate (25%)

M – Mining Supply (Based on fixed mining supply minted per person)

In contrast to Bitcoin which created a fixed supply of coins for the entire global population, Pi creates a fixed supply of Pi for each person that joins the network up to the first 100 Million participants. In other words, for each person that joins the Pi Network, a fixed amount of Pi is pre-minted. This supply is then released over the lifetime of that member based on their level of engagement and contribution to network security. The supply is released using an exponentially decreasing function similar to Bitcoin’s over the member’s lifetime.

R – Referral Supply (Based on fixed referral reward minted per person and shared b/w referrer and referee)

In order for a currency to have value, it must be widely distributed. To incentivize this goal, the protocol also generates a fixed amount of Pi that serves as a referral bonus for both the referrer and the referee (or both parent and offspring 🙂 This shared pool can be mined by both parties over their lifetime – when both parties are actively mining. Both referrer and referee are able to draw upon this pool in order to avoid exploitative models where referrers are able to “prey” on their referees. The referral bonus serves as a network-level incentive to grow the Pi Network while also incentivizing engagement among members in actively securing the network.

D – Developer Reward Supply (Additional Pi minted to support ongoing development)

Pi will fund its ongoing development with a “Developer Reward” that is minted alongside each coin that is minted for mining and referrals. Traditionally, cryptocurrency protocols have minted a fixed amount of supply that is immediately placed into treasury. Because Pi’s total supply is dependent on the number of members in the network, Pi progressively mints its developer reward as the network scales. The progressive minting of Pi’s developer reward is meant to align the incentives of Pi’s contributors with the overall health of the network.

f is a logarithmically decreasing function – early members earn more

While Pi seeks to avoid extreme concentrations of wealth, the network also seeks to reward earlier members and their contributions with a relatively larger share of Pi. When networks such as Pi are in their early days, they tend to provide a lower utility to participants. For example, imagine having the very first telephone in the world. It would be a great technological innovation but not extremely useful. However, as more people acquire telephones, each telephone holder gets more utility out of the network. In order to reward people that come to the network early, Pi’s individual mining reward and referral rewards decrease as a function of the number of people in the network. In other words, there is a certain amount of Pi that is reserved for each “slot” in the Pi Network.

Utility: Pooling and monetizing our time online

Today, everyone is sitting on a veritable treasure trove of untapped resources. Each of us spend hours day on our phones. While on our phones, each of our views, posts or clicks creates extraordinary profits for large corporations. At Pi, we believe that people have the right to capture value created from their resources.

We all know that we can do more together than we can alone. On today’s web, massive corporations like Google, Amazon, Facebook have immense leverage against individual consumers. As a result, they are able to capture the lionshare of value created by individual consumers on the web. Pi levels the playing field by allowing its members to pool their collective resources so they can get a share of the value that they create.

The graphic below is the Pi Stack, where we see particularly promising opportunities for helping our members capture value. Below, we go into each of these areas in more detail.

Introducing the Pi Stack – Unleashing underutilized resources

Pi Ledger And Shared Trust Graph – Scaling Trust Across The Web

One of the biggest challenges on the internet is knowing who to trust. Today, we rely on the  rating systems of providers such as Amazon, eBay, Yelp, to know who we can transact with on the internet. Despite the fact that we, customers, do the hard work of rating and reviewing our peers, these internet intermediaries capture the lionshare of the value created this work.

Pi’s consensus algorithm, described above, creates a native trust layer that scales trust on the web without intermediaries. While the value of just one individual’s Security Circle is small, the aggregate of our individual security circles build a global “trust graph” that help people understand who on the Pi Network can be trusted. The Pi Network’s global trust graph will facilitate transactions between strangers that would not have otherwise been possible. Pi’s native currency, in turn, allows everyone who contributes to the security of the network to capture a share of the value they have helped create.

Pi’s Attention Marketplace – Bartering Unutilized Attention And Time

Pi allows its members to pool their collective attention to create an attention market much more valuable than any individual’s attention alone. The first application built on this layer will be a scarce social media channel currently hosted on the home screen of the application. You can think of the scarce social media channel as Instagram with one global post at a time. Pioneers can wager Pi to engage the attention of other members of the network, by sharing content (e.g., text, images, videos) or asking questions that seek to tap into the collective wisdom of the community. On the Pi Network, everyone has the opportunity to be an influencer or to tap into the wisdom of the crowd. To date, Pi’s Core Team has been using this channel to poll the community’s opinion on design choices for Pi (e.g. the community voted on the design and colors of the Pi logo.) We have received many valuable responses and feedback from the community on the project. One possible future direction is to open the attention market for any Pioneer to use Pi to post their content, while expanding the number of channels hosted on the Pi Network.

In addition to bartering attention with their peers, Pioneers may also opt into bartering with companies that are seeking their attention. The average American sees between 4,000 and 10,000 ads a day. Companies fight for our attention and pay tremendous amounts of money for it. But we, the customers, receive no value from these transactions. In Pi’s attention marketplace, companies seeking to reach Pioneers will have to compensate their audience in Pi. Pi’s advertising marketplace will be strictly opt-in only and will provide an opportunity for Pioneers to monetize one of their greatest untapped resources: their attention.

Pi’s Barter Marketplace – Build Your Personal Virtual Storefront

In addition to contributing trust and attention to the Pi Network, we expect Pioneers to be able to contribute their unique skills and services in the future. Pi’s mobile application will also serve as a Point of Sales where Pi’s members can offer their untapped goods and services via a “virtual storefront” to other members of the Pi Network. For example, a member offer up an underutilized room in their apartment for rent to other members on the Pi Network. In addition to real assets, members of the Pi Network will also be able to offer skills and services via their virtual storefronts. For example, a member of the Pi Network could offer their programming or design skills on the Pi marketplace. Overtime, the value of Pi will be supported by a growing basket of goods and services.

Pi’s Decentralized App Store – Lowering The Barrier Of Entry For Creators

The Pi Network’s shared currency, trust graph, and marketplace will be the soil for a broader ecosystem of decentralized applications. Today, anyone that wants to start an application needs to bootstrap its technical infrastructure and community from scratch. Pi’s decentralized applications store will allow Dapp developers to leverage Pi’s existing infrastructure as well as the shared resources of the community and users. Entrepreneurs and developers can propose new Dapps to the community with requests for access to the network’s shared resources. Pi will also build its Dapps with some degree of interoperability so that Dapps are able to reference data, assets, and processes in other decentralized applications.

Governance – Cryptocurrency for and by the people

Challenges w/ 1st Generation Governance models

Trust is the foundation of any successful monetary system. One of the most important factors engendering trust is governance, or the process by which changes are implemented to the protocol over time. Despite its importance, governance is often one of the most overlooked aspects of cryptoeconomic systems.

First generation networks such as Bitcoin largely avoided formal (or “on-chain”) governance mechanisms in favor of informal (or “off-chain”) mechanisms arising from a combination of role and incentive design. By most measures, Bitcoin’s governance mechanisms has been quite successful, allowing the protocol to grow dramatically in scale and value since its inception. However, there have also been some challenges. The economic concentration of Bitcoin has led to a concentration of political power. The result is that everyday people can get caught in the middle of destructive battles between massive holders of Bitcoin. One of the most recent examples of this challenge has been the ongoing battle between Bitcoin and Bitcoin Cash. These civil wars can end in a fork where or where the blockchain. For token holders, hard forks are inflationary and can threaten the value of their holdings.

Pi’s Governance Model – a two-phase plan

In an article challenging the merits of on-chain governance, Vlad Zamfir, one of Ethereum’s core developers, argues that blockchain governance “is not an abstract design problem. It’s an applied social problem.” One of Vlad’s key points is that it is very difficult to design governance systems “a priori” or before observations of the particular challenges arising from a specific political system. One historical example is in the founding of the United States. The first experiment with democracy in the United States, the Articles of Confederation, failed after an eight-year experiment. The Founding Fathers of the United States were then able to draw upon the lessons of the Article of Confederation to craft the the Constitution – a much more successful experiment.

To build an enduring governance model, Pi will pursue a two-phase plan.

Provisional Governance Model (< 5M members)

Until the network hits a critical mass of 5M members, Pi will operate under a provisional governance model. This model will most closely resemble “off-chain” governance models currently employed by protocols like Bitcoin and Ethereum, with Pi’s Core Team playing an important role in guiding the development of the protocol. However,, Pi’s Core Team will still rely heavily on the input of the community. The Pi mobile application itself is where Pi’s core team has been soliciting community input and engaging with Pioneers. Pi embraces community critiques and suggestions, which is implemented by the open-for-comments features of Pi’s landing page, FAQs and white paper. Whenever people browse these materials on Pi’s websites, they can submit comment on a specific section right there to ask for questions and make suggestions. Offline Pioneer meetups that Pi’s core team have been organizing will also be an important channel for community input.

Additionally, Pi’s Core Team will develop more formal governance mechanics. One potential governance system is liquid democracy. In liquid democracy, every Pioneer will have the ability to either vote on an issue directly or to delegate their vote to another member of the network. Liquid democracy would allow for both broad and efficient membership from Pi’s community.

Pi’s “Constitutional Convention” (> 5M members)

Upon hitting 5M members, a provisional committee will be formed based on previous contributions to the Pi Network. This committee will be responsible for soliciting and proposing suggestions from and to the wider community. It will also organize a series of on- and offline conversations where Pi’s members will be able to weigh on Pi’s long-term constitution. Given Pi’s global user base, the Pi Network will conduct these conventions at multiple locations across the world to ensure accessibility. In addition to hosting in-person conventions, Pi will also use its mobile application as a platform for allowing Pi’s member to participate in the process remotely. Whether in-person or online, Pi’s community members will have the ability to participate in the crafting Pi’s long-term governance structure.

Roadmap / Deployment plan

Phase 1 – Design, Distribution, Trust Graph Bootstrap.

The Pi server is operating as a faucet emulating the behavior of the decentralized system as it will function once its live. During this phase improvements in the user experience and behavior are possible and relatively easy to make compared to the stable phase of the main net. All minting of coins to users will be migrated to the live net once it launches. In other words, the livenet will pre-mint  in its genesis block all account holder balances generated during Phase 1, and continue operating just like the current system but fully decentralized. Pi is not listed on exchanges during this phase and it is impossible to “buy” Pi with any other currency.

Phase 2 – Testnet

Before we launch the main net, the Node software will be deployed on a test net. The test net will use the same exact trust graph as the main net but on a testing Pi coin. Pi core team will host several nodes on the test net, but will encourage more Pioneers to start their own nodes on the testnet. In fact, in order for any node to join the main net, they are advised to begin on the testnet. The test net will be run in parallel to the Pi emulator in phase one, and periodically, e.g. daily, the results from both systems will be compared to catch the gaps and misses of the test net, which will allow Pi developers to propose and implement fixes.  After a thorough concurrent run of both systems, testnet will reach a state where its results consistently match the emulator’s. At that time when the community feels its ready, Pi will migrate to the next phase.

Phase 3 – Mainnet

When the community feels the software is ready for production, and it has been thoroughly tested on the testnet, the official mainnet of the Pi network will be launched. An important detail is that, in the transition into the mainnet, only accounts validated to belong to distinct real individuals will be honored. After this point, the faucet and Pi network emulator of Phase 1 will be shut down and the system will continue on its own forever. Future updates to the protocol will be contributed by the Pi developer community and Pi’s core team, and will be proposed by the committee. Their implementation and deployment will depend on nodes updating the mining software just like any other blockchains. No central authority will be controlling the currency and it will be fully decentralized. Balances of fake users or duplicate users will be discarded. This is the phase when Pi can be connected to exchanges and be exchanged for other currencies.