{ localUrl: '../page/peano_arithmetic.html', arbitalUrl: 'https://arbital.com/p/peano_arithmetic', rawJsonUrl: '../raw/3ft.json', likeableId: '0', likeableType: 'page', myLikeValue: '0', likeCount: '0', dislikeCount: '0', likeScore: '0', individualLikes: [], pageId: 'peano_arithmetic', edit: '2', editSummary: '', prevEdit: '1', currentEdit: '2', wasPublished: 'true', type: 'wiki', title: 'Peano Arithmetic', clickbait: 'A system for proving theorems about arithmetic, which is strong enough to include self-reference.', textLength: '1126', alias: 'peano_arithmetic', externalUrl: '', sortChildrenBy: 'likes', hasVote: 'false', voteType: '', votesAnonymous: 'false', editCreatorId: 'PatrickLaVictoir', editCreatedAt: '2016-05-06 18:17:18', pageCreatorId: 'PatrickLaVictoir', pageCreatedAt: '2016-05-06 17:57:22', seeDomainId: '0', editDomainId: 'NateSoares', submitToDomainId: '0', isAutosave: 'false', isSnapshot: 'false', isLiveEdit: 'true', isMinorEdit: 'false', indirectTeacher: 'false', todoCount: '0', isEditorComment: 'false', isApprovedComment: 'true', isResolved: 'false', snapshotText: '', anchorContext: '', anchorText: '', anchorOffset: '0', mergedInto: '', isDeleted: 'false', viewCount: '64', text: 'Peano Arithmetic is a particular set of axioms and rules which allow you to prove theorems about the natural numbers.\n\nThese rules were formulated by the Italian mathematician [Giuseppe Peano](https://en.wikipedia.org/wiki/Giuseppe_Peano) in 1889. They can be expressed as follows:\n\nLet our language consist of the symbols $\\left\\{(,),\\wedge,\\vee,\\neg,\\to,\\leftrightarrow,\\in,\\forall,\\exists,=,+,\\cdot,O,S,N \\right\\}$ and an infinite set of variable symbols, which we will denote as $x, y, z, \\dots$ (since three symbols is usually enough to denote infinitely many symbols). \n\nWe would like to interpret these symbols as representing our intuitive notions of logical and arithmetical operators, interpreting $O$ as the number 0, $S$ as the successor operation (thus $SO$ represents 1, $SSO$ represents 2, etc), and $N$ as the set of natural numbers.\n\nWe would furthermore like to create some formal rules such that we can derive certain true statements of arithmetic, like $SO+SO=SSO$ or $\\forall x \\in N\\; Sx \\cdot Sx = x\\cdot x + SSO \\cdot x + SO$, but not derive false statements like $\\exists x\\in N \\; SSO\\cdot x = SSSO$.', metaText: '', isTextLoaded: 'true', isSubscribedToDiscussion: 'false', isSubscribedToUser: 'false', isSubscribedAsMaintainer: 'false', discussionSubscriberCount: '1', maintainerCount: '1', userSubscriberCount: '0', lastVisit: '', hasDraft: 'false', votes: [], voteSummary: 'null', muVoteSummary: '0', voteScaling: '0', currentUserVote: '-2', voteCount: '0', lockedVoteType: '', maxEditEver: '0', redLinkCount: '0', lockedBy: '', lockedUntil: '', nextPageId: '', prevPageId: '', usedAsMastery: 'false', proposalEditNum: '0', permissions: { edit: { has: 'false', reason: 'You don't have domain permission to edit this page' }, proposeEdit: { has: 'true', reason: '' }, delete: { has: 'false', reason: 'You don't have domain permission to delete this page' }, comment: { has: 'false', reason: 'You can't comment in this domain because you are not a member' }, proposeComment: { has: 'true', reason: '' } }, summaries: {}, creatorIds: [ 'PatrickLaVictoir' ], childIds: [], parentIds: [], commentIds: [], questionIds: [], tagIds: [], relatedIds: [], markIds: [], explanations: [], learnMore: [], requirements: [], subjects: [], lenses: [], lensParentId: '', pathPages: [], learnMoreTaughtMap: {}, learnMoreCoveredMap: {}, learnMoreRequiredMap: {}, editHistory: {}, domainSubmissions: {}, answers: [], answerCount: '0', commentCount: '0', newCommentCount: '0', linkedMarkCount: '0', changeLogs: [ { likeableId: '0', likeableType: 'changeLog', myLikeValue: '0', likeCount: '0', dislikeCount: '0', likeScore: '0', individualLikes: [], id: '9632', pageId: 'peano_arithmetic', userId: 'PatrickLaVictoir', edit: '2', type: 'newEdit', createdAt: '2016-05-06 18:17:18', auxPageId: '', oldSettingsValue: '', newSettingsValue: '' }, { likeableId: '0', likeableType: 'changeLog', myLikeValue: '0', likeCount: '0', dislikeCount: '0', likeScore: '0', individualLikes: [], id: '9629', pageId: 'peano_arithmetic', userId: 'PatrickLaVictoir', edit: '1', type: 'newEdit', createdAt: '2016-05-06 17:57:22', auxPageId: '', oldSettingsValue: '', newSettingsValue: '' } ], feedSubmissions: [], searchStrings: {}, hasChildren: 'false', hasParents: 'false', redAliases: {}, improvementTagIds: [], nonMetaTagIds: [], todos: [], slowDownMap: 'null', speedUpMap: 'null', arcPageIds: 'null', contentRequests: {} }