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[o]" accesskey="o"><span class="vector-icon mw-ui-icon-logIn mw-ui-icon-wikimedia-logIn"></span> <span>Log på</span></a></li> </ul> </div> </div> </div> </div> </nav> </div> </header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"><div id="mw-dismissablenotice-anonplace"></div><script>(function(){var node=document.getElementById("mw-dismissablenotice-anonplace");if(node){node.outerHTML="\u003Cdiv class=\"mw-dismissable-notice\"\u003E\u003Cdiv class=\"mw-dismissable-notice-close\"\u003E[\u003Ca tabindex=\"0\" role=\"button\"\u003ELuk\u003C/a\u003E]\u003C/div\u003E\u003Cdiv class=\"mw-dismissable-notice-body\"\u003E\u003C!-- CentralNotice --\u003E\u003Cdiv id=\"localNotice\" data-nosnippet=\"\"\u003E\u003Cdiv class=\"sitenotice\" lang=\"da\" dir=\"ltr\"\u003E\u003Cp\u003EDu kan deltage i Palnatokes traditionelle \u003Ca href=\"/wiki/Bruger:Palnatoke/Julequiz\" class=\"mw-redirect\" title=\"Bruger:Palnatoke/Julequiz\"\u003Ejulequiz\u003C/a\u003E.\u003Ci\u003E \u003Csmall\u003E(\u003Ca href=\"/wiki/Hj%C3%A6lp:Sitenotice\" title=\"Hjælp:Sitenotice\"\u003ELæs her om sitenotice\u003C/a\u003E)\u003C/small\u003E\u003C/i\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/div\u003E\u003C/div\u003E\u003C/div\u003E";}}());</script></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Websted"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Indhold" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Indhold</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">flyt til sidebjælken</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">skjul</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">Indledning</div> </a> </li> <li id="toc-Se_også" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Se_også"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Se også</span> </div> </a> <ul id="toc-Se_også-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Indhold" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Vis/skjul indholdsfortegnelsen" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Vis/skjul indholdsfortegnelsen</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Bijektiv</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Gå til en artikel på et andet sprog. Tilgængelig på 55 sprog" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-55" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">55 sprog</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AA%D9%82%D8%A7%D8%A8%D9%84_(%D8%AF%D8%A7%D9%84%D8%A9)" title="تقابل (دالة) – arabisk" lang="ar" hreflang="ar" data-title="تقابل (دالة)" data-language-autonym="العربية" data-language-local-name="arabisk" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%91%D1%96%D0%B5%D0%BA%D1%86%D1%8B%D1%8F" title="Біекцыя – belarusisk" lang="be" hreflang="be" data-title="Біекцыя" data-language-autonym="Беларуская" data-language-local-name="belarusisk" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%91%D0%B8%D0%B5%D0%BA%D1%86%D0%B8%D1%8F" title="Биекция – bulgarsk" lang="bg" hreflang="bg" data-title="Биекция" data-language-autonym="Български" data-language-local-name="bulgarsk" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Bijekcija" title="Bijekcija – bosnisk" lang="bs" hreflang="bs" data-title="Bijekcija" data-language-autonym="Bosanski" data-language-local-name="bosnisk" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Funci%C3%B3_bijectiva" title="Funció bijectiva – catalansk" lang="ca" hreflang="ca" data-title="Funció bijectiva" data-language-autonym="Català" data-language-local-name="catalansk" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-co mw-list-item"><a href="https://co.wikipedia.org/wiki/Biiezzioni" title="Biiezzioni – korsikansk" lang="co" hreflang="co" data-title="Biiezzioni" data-language-autonym="Corsu" data-language-local-name="korsikansk" class="interlanguage-link-target"><span>Corsu</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Bijekce" title="Bijekce – tjekkisk" lang="cs" hreflang="cs" data-title="Bijekce" data-language-autonym="Čeština" data-language-local-name="tjekkisk" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Bijektive_Funktion" title="Bijektive Funktion – tysk" lang="de" hreflang="de" data-title="Bijektive Funktion" data-language-autonym="Deutsch" data-language-local-name="tysk" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-en mw-list-item"><a href="https://en.wikipedia.org/wiki/Bijection" title="Bijection – engelsk" lang="en" hreflang="en" data-title="Bijection" data-language-autonym="English" data-language-local-name="engelsk" class="interlanguage-link-target"><span>English</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Dissur%C4%B5eto" title="Dissurĵeto – esperanto" lang="eo" hreflang="eo" data-title="Dissurĵeto" data-language-autonym="Esperanto" data-language-local-name="esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Funci%C3%B3n_biyectiva" title="Función biyectiva – spansk" lang="es" hreflang="es" data-title="Función biyectiva" data-language-autonym="Español" data-language-local-name="spansk" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Bijektiivne_funktsioon" title="Bijektiivne funktsioon – estisk" lang="et" hreflang="et" data-title="Bijektiivne funktsioon" data-language-autonym="Eesti" data-language-local-name="estisk" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Bijekzio" title="Bijekzio – baskisk" lang="eu" hreflang="eu" data-title="Bijekzio" data-language-autonym="Euskara" data-language-local-name="baskisk" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AA%D9%86%D8%A7%D8%B8%D8%B1_%D8%AF%D9%88%D8%B3%D9%88%DB%8C%D9%87" title="تناظر دوسویه – persisk" lang="fa" hreflang="fa" data-title="تناظر دوسویه" data-language-autonym="فارسی" data-language-local-name="persisk" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Bijektio" title="Bijektio – finsk" lang="fi" hreflang="fi" data-title="Bijektio" data-language-autonym="Suomi" data-language-local-name="finsk" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Bijection" title="Bijection – fransk" lang="fr" hreflang="fr" data-title="Bijection" data-language-autonym="Français" data-language-local-name="fransk" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Funci%C3%B3n_bixectiva" title="Función bixectiva – galicisk" lang="gl" hreflang="gl" data-title="Función bixectiva" data-language-autonym="Galego" data-language-local-name="galicisk" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A4%D7%95%D7%A0%D7%A7%D7%A6%D7%99%D7%94_%D7%97%D7%93-%D7%97%D7%93-%D7%A2%D7%A8%D7%9B%D7%99%D7%AA_%D7%95%D7%A2%D7%9C" title="פונקציה חד-חד-ערכית ועל – hebraisk" lang="he" hreflang="he" data-title="פונקציה חד-חד-ערכית ועל" data-language-autonym="עברית" data-language-local-name="hebraisk" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%A6%E0%A5%8D%E0%A4%B5%E0%A4%BF%E0%A4%85%E0%A4%82%E0%A4%A4%E0%A4%A5%E0%A4%95%E0%A5%8D%E0%A4%B7%E0%A5%87%E0%A4%AA%E0%A4%A3" title="द्विअंतथक्षेपण – hindi" lang="hi" hreflang="hi" data-title="द्विअंतथक्षेपण" data-language-autonym="हिन्दी" data-language-local-name="hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Bijekcija" title="Bijekcija – kroatisk" lang="hr" hreflang="hr" data-title="Bijekcija" data-language-autonym="Hrvatski" data-language-local-name="kroatisk" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Bijekci%C3%B3" title="Bijekció – ungarsk" lang="hu" hreflang="hu" data-title="Bijekció" data-language-autonym="Magyar" data-language-local-name="ungarsk" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%93%D5%B8%D5%AD%D5%B4%D5%AB%D5%A1%D6%80%D5%AA%D5%A5%D6%84_%D5%B0%D5%A1%D5%B4%D5%A1%D5%BA%D5%A1%D5%BF%D5%A1%D5%BD%D5%AD%D5%A1%D5%B6%D5%B8%D6%82%D5%A9%D5%B5%D5%B8%D6%82%D5%B6" title="Փոխմիարժեք համապատասխանություն – armensk" lang="hy" hreflang="hy" data-title="Փոխմիարժեք համապատասխանություն" data-language-autonym="Հայերեն" data-language-local-name="armensk" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-ia mw-list-item"><a href="https://ia.wikipedia.org/wiki/Bijection" title="Bijection – interlingua" lang="ia" hreflang="ia" data-title="Bijection" data-language-autonym="Interlingua" data-language-local-name="interlingua" class="interlanguage-link-target"><span>Interlingua</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Bijeksi" title="Bijeksi – indonesisk" lang="id" hreflang="id" data-title="Bijeksi" data-language-autonym="Bahasa Indonesia" data-language-local-name="indonesisk" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-io mw-list-item"><a href="https://io.wikipedia.org/wiki/Bijektio" title="Bijektio – ido" lang="io" hreflang="io" data-title="Bijektio" data-language-autonym="Ido" data-language-local-name="ido" class="interlanguage-link-target"><span>Ido</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Gagnt%C3%A6k_v%C3%B6rpun" title="Gagntæk vörpun – islandsk" lang="is" hreflang="is" data-title="Gagntæk vörpun" data-language-autonym="Íslenska" data-language-local-name="islandsk" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Corrispondenza_biunivoca" title="Corrispondenza biunivoca – italiensk" lang="it" hreflang="it" data-title="Corrispondenza biunivoca" data-language-autonym="Italiano" data-language-local-name="italiensk" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E5%85%A8%E5%8D%98%E5%B0%84" title="全単射 – japansk" lang="ja" hreflang="ja" data-title="全単射" data-language-autonym="日本語" data-language-local-name="japansk" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D3%A8%D0%B7%D0%B0%D1%80%D0%B0_%D0%B1%D1%96%D1%80%D0%BC%D3%99%D0%BD%D0%B4%D1%96_%D1%81%D3%99%D0%B9%D0%BA%D0%B5%D1%81%D1%82%D1%96%D0%BA" title="Өзара бірмәнді сәйкестік – kasakhisk" lang="kk" hreflang="kk" data-title="Өзара бірмәнді сәйкестік" data-language-autonym="Қазақша" data-language-local-name="kasakhisk" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%A0%84%EB%8B%A8%EC%82%AC_%ED%95%A8%EC%88%98" title="전단사 함수 – koreansk" lang="ko" hreflang="ko" data-title="전단사 함수" data-language-autonym="한국어" data-language-local-name="koreansk" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Functio_biiectiva" title="Functio biiectiva – latin" lang="la" hreflang="la" data-title="Functio biiectiva" data-language-autonym="Latina" data-language-local-name="latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Bigezzion" title="Bigezzion – Lombard" lang="lmo" hreflang="lmo" data-title="Bigezzion" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Bijekcija" title="Bijekcija – litauisk" lang="lt" hreflang="lt" data-title="Bijekcija" data-language-autonym="Lietuvių" data-language-local-name="litauisk" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%91%D0%B8%D1%98%D0%B5%D0%BA%D1%86%D0%B8%D1%98%D0%B0" title="Бијекција – makedonsk" lang="mk" hreflang="mk" data-title="Бијекција" data-language-autonym="Македонски" data-language-local-name="makedonsk" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Bijectie" title="Bijectie – nederlandsk" lang="nl" hreflang="nl" data-title="Bijectie" data-language-autonym="Nederlands" data-language-local-name="nederlandsk" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Bijeksjon" title="Bijeksjon – nynorsk" lang="nn" hreflang="nn" data-title="Bijeksjon" data-language-autonym="Norsk nynorsk" data-language-local-name="nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Bijeksjon" title="Bijeksjon – bokmål" lang="nb" hreflang="nb" data-title="Bijeksjon" data-language-autonym="Norsk bokmål" data-language-local-name="bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Bijeccion" title="Bijeccion – occitansk" lang="oc" hreflang="oc" data-title="Bijeccion" data-language-autonym="Occitan" data-language-local-name="occitansk" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Funkcja_wzajemnie_jednoznaczna" title="Funkcja wzajemnie jednoznaczna – polsk" lang="pl" hreflang="pl" data-title="Funkcja wzajemnie jednoznaczna" data-language-autonym="Polski" data-language-local-name="polsk" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Fun%C3%A7%C3%A3o_bijectiva" title="Função bijectiva – portugisisk" lang="pt" hreflang="pt" data-title="Função bijectiva" data-language-autonym="Português" data-language-local-name="portugisisk" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Coresponden%C8%9B%C4%83_biunivoc%C4%83" title="Corespondență biunivocă – rumænsk" lang="ro" hreflang="ro" data-title="Corespondență biunivocă" data-language-autonym="Română" data-language-local-name="rumænsk" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%91%D0%B8%D0%B5%D0%BA%D1%86%D0%B8%D1%8F" title="Биекция – russisk" lang="ru" hreflang="ru" data-title="Биекция" data-language-autonym="Русский" data-language-local-name="russisk" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Bijection" title="Bijection – skotsk" lang="sco" hreflang="sco" data-title="Bijection" data-language-autonym="Scots" data-language-local-name="skotsk" class="interlanguage-link-target"><span>Scots</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Bijective_function" title="Bijective function – Simple English" lang="en-simple" hreflang="en-simple" data-title="Bijective function" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Bijekt%C3%ADvne_zobrazenie" title="Bijektívne zobrazenie – slovakisk" lang="sk" hreflang="sk" data-title="Bijektívne zobrazenie" data-language-autonym="Slovenčina" data-language-local-name="slovakisk" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Bijektivna_preslikava" title="Bijektivna preslikava – slovensk" lang="sl" hreflang="sl" data-title="Bijektivna preslikava" data-language-autonym="Slovenščina" data-language-local-name="slovensk" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%91%D0%B8%D1%98%D0%B5%D0%BA%D1%86%D0%B8%D1%98%D0%B0" title="Бијекција – serbisk" lang="sr" hreflang="sr" data-title="Бијекција" data-language-autonym="Српски / srpski" data-language-local-name="serbisk" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Bijektiv_funktion" title="Bijektiv funktion – svensk" lang="sv" hreflang="sv" data-title="Bijektiv funktion" data-language-autonym="Svenska" data-language-local-name="svensk" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%87%E0%AE%B0%E0%AF%81%E0%AE%B5%E0%AE%B4%E0%AE%BF%E0%AE%95%E0%AF%8D%E0%AE%95%E0%AF%8B%E0%AE%AA%E0%AF%8D%E0%AE%AA%E0%AF%81" title="இருவழிக்கோப்பு – tamil" lang="ta" hreflang="ta" data-title="இருவழிக்கோப்பு" data-language-autonym="தமிழ்" data-language-local-name="tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%9F%E0%B8%B1%E0%B8%87%E0%B8%81%E0%B9%8C%E0%B8%8A%E0%B8%B1%E0%B8%99%E0%B8%AB%E0%B8%99%E0%B8%B6%E0%B9%88%E0%B8%87%E0%B8%95%E0%B9%88%E0%B8%AD%E0%B8%AB%E0%B8%99%E0%B8%B6%E0%B9%88%E0%B8%87%E0%B8%97%E0%B8%B1%E0%B9%88%E0%B8%A7%E0%B8%96%E0%B8%B6%E0%B8%87" title="ฟังก์ชันหนึ่งต่อหนึ่งทั่วถึง – thai" lang="th" hreflang="th" data-title="ฟังก์ชันหนึ่งต่อหนึ่งทั่วถึง" data-language-autonym="ไทย" data-language-local-name="thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Birebir_%C3%B6rten_fonksiyon" title="Birebir örten fonksiyon – tyrkisk" lang="tr" hreflang="tr" data-title="Birebir örten fonksiyon" data-language-autonym="Türkçe" data-language-local-name="tyrkisk" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%91%D1%96%D1%94%D0%BA%D1%86%D1%96%D1%8F" title="Бієкція – ukrainsk" lang="uk" hreflang="uk" data-title="Бієкція" data-language-autonym="Українська" data-language-local-name="ukrainsk" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Song_%C3%A1nh" title="Song ánh – vietnamesisk" lang="vi" hreflang="vi" data-title="Song ánh" data-language-autonym="Tiếng Việt" data-language-local-name="vietnamesisk" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%8F%8C%E5%B0%84" title="双射 – kinesisk" lang="zh" hreflang="zh" data-title="双射" data-language-autonym="中文" data-language-local-name="kinesisk" class="interlanguage-link-target"><span>中文</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E5%B0%8D%E5%B0%84%E5%87%BD%E6%95%B8" title="對射函數 – kantonesisk" lang="yue" hreflang="yue" data-title="對射函數" data-language-autonym="粵語" data-language-local-name="kantonesisk" class="interlanguage-link-target"><span>粵語</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q180907#sitelinks-wikipedia" title="Redigér sproglinks" class="wbc-editpage">Redigér links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Navnerum"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Bijektiv" title="Se indholdssiden [c]" accesskey="c"><span>Artikel</span></a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Diskussion:Bijektiv" rel="discussion" title="Diskussion om indholdet på siden [t]" accesskey="t"><span>Diskussion</span></a></li> </ul> </div> </div> <div id="vector-variants-dropdown" class="vector-dropdown emptyPortlet" > <input type="checkbox" id="vector-variants-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-variants-dropdown" class="vector-dropdown-checkbox " aria-label="Ændr sprogvariant" > <label id="vector-variants-dropdown-label" for="vector-variants-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">dansk</span> </label> <div class="vector-dropdown-content"> <div id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> </div> </div> </nav> </div> <div id="right-navigation" class="vector-collapsible"> <nav aria-label="Visninger"> <div id="p-views" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-views" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-view" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Bijektiv"><span>Læs</span></a></li><li id="ca-ve-edit" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Bijektiv&veaction=edit" title="Redigér denne side [v]" accesskey="v"><span>Redigér</span></a></li><li id="ca-edit" class="collapsible vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Bijektiv&action=edit" title="Rediger kildekoden for denne side [e]" accesskey="e"><span>Rediger kildekode</span></a></li><li id="ca-history" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Bijektiv&action=history" title="Tidligere versioner af denne side [h]" accesskey="h"><span>Se historik</span></a></li> </ul> </div> </div> </nav> <nav class="vector-page-tools-landmark" aria-label="Sideværktøjer"> <div id="vector-page-tools-dropdown" class="vector-dropdown vector-page-tools-dropdown" > <input type="checkbox" id="vector-page-tools-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-tools-dropdown" class="vector-dropdown-checkbox " aria-label="Værktøjer" > <label id="vector-page-tools-dropdown-label" for="vector-page-tools-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">Værktøjer</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-tools-unpinned-container" class="vector-unpinned-container"> <div id="vector-page-tools" class="vector-page-tools vector-pinnable-element"> <div 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class="selected vector-more-collapsible-item mw-list-item"><a href="/wiki/Bijektiv"><span>Læs</span></a></li><li id="ca-more-ve-edit" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Bijektiv&veaction=edit" title="Redigér denne side [v]" accesskey="v"><span>Redigér</span></a></li><li id="ca-more-edit" class="collapsible vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Bijektiv&action=edit" title="Rediger kildekoden for denne side [e]" accesskey="e"><span>Rediger kildekode</span></a></li><li id="ca-more-history" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Bijektiv&action=history"><span>Se historik</span></a></li> </ul> </div> </div> <div id="p-tb" class="vector-menu mw-portlet mw-portlet-tb" > <div class="vector-menu-heading"> Generelt </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-whatlinkshere" class="mw-list-item"><a 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10%;border-collapse:collapse;border:1px solid #c0c090;background-color:#f8eaba;min-width:80%;box-sizing:border-box}.mw-parser-output .tmbox.mbox-small{min-width:0}.mw-parser-output .mediawiki .mbox-inside .tmbox{margin:2px 0;width:100%}.mw-parser-output .mbox-inside .tmbox.mbox-small{line-height:1.5em;font-size:100%}.mw-parser-output table.tmbox-speedy{border:2px solid #b32424;background-color:#fee7e6}.mw-parser-output table.tmbox-delete{border:2px solid #b32424}.mw-parser-output table.tmbox-content{border:2px solid #f28500}.mw-parser-output table.tmbox-style{border:2px solid #fc3}.mw-parser-output table.tmbox-move{border:2px solid #9932cc}.mw-parser-output table.tmbox-protection,.mw-parser-output table.tmbox-notice{border:1px solid #c0c090}.mw-parser-output table.fmbox{clear:both;margin:0.2em 0;width:100%;border:1px solid #a2a9b1;background-color:#f8f9fa;box-sizing:border-box}.mw-parser-output table.fmbox-system{background-color:#f8f9fa}.mw-parser-output table.fmbox-warning{border:1px solid #bb7070;background-color:#ffdbdb}.mw-parser-output table.fmbox-editnotice{background-color:transparent}.mw-parser-output div.mw-warning-with-logexcerpt,.mw-parser-output div.mw-lag-warn-high,.mw-parser-output div.mw-cascadeprotectedwarning,.mw-parser-output div/**/#mw-protect-cascadeon,.mw-parser-output div.titleblacklist-warning,.mw-parser-output div.locked-warning{clear:both;margin:0.2em 0;border:1px solid #bb7070;background-color:#ffdbdb;padding:0.25em 0.9em;box-sizing:border-box}html body.mediawiki .mw-parser-output .mbox-small{clear:right;float:right;margin:4px 0 4px 1em;box-sizing:border-box;width:238px;font-size:88%;line-height:1.25em}html body.mediawiki .mw-parser-output .mbox-small-left{margin:4px 1em 4px 0;box-sizing:border-box;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .compact-ambox table .mbox-image,.mw-parser-output .compact-ambox table .mbox-imageright,.mw-parser-output .compact-ambox table .mbox-empty-cell{display:none}.mw-parser-output .compact-ambox table.ambox{border:none;border-collapse:collapse;background-color:transparent;margin:0 0 0 1.6em!important;padding:0!important;width:auto;display:block}body.mediawiki .mw-parser-output .compact-ambox table.mbox-small-left{font-size:100%;width:auto;margin:0}.mw-parser-output .compact-ambox table .mbox-text{padding:0;margin:0}.mw-parser-output .compact-ambox table .mbox-text-span{display:list-item;line-height:1.5em;list-style-type:square}.mw-parser-output .skin-vector .compact-ambox table .mbox-text-span{list-style-type:disc}.mw-parser-output .compact-ambox .hide-when-compact{display:none}.mw-parser-output .template-documentation{clear:both;margin:1em 0 0 0;border:1px solid #aaa;background-color:#ecfcf4;padding:1em}</style> <figure typeof="mw:File/Thumb"><a href="/wiki/Fil:Bijection.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Bijection.svg/200px-Bijection.svg.png" decoding="async" width="200" height="200" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Bijection.svg/300px-Bijection.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Bijection.svg/400px-Bijection.svg.png 2x" data-file-width="200" data-file-height="200" /></a><figcaption>En bijektiv funktion.</figcaption></figure> <p>En <a href="/wiki/Afbildning_(matematik)" class="mw-redirect" title="Afbildning (matematik)">afbildning</a> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi :X\to Y}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ϕ</mi> <mo>:</mo> <mi>X</mi> <mo stretchy="false">→</mo> <mi>Y</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \phi :X\to Y}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b98600ef34bb9c70ab402e2f46de411a750ca3ab" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:10.69ex; height:2.509ex;" alt="{\displaystyle \phi :X\to Y}"></span> er <b>bijektiv</b> (<b>enentydig</b>), når den både er <a href="/wiki/Injektiv" title="Injektiv">injektiv</a> og <a href="/wiki/Surjektiv" title="Surjektiv">surjektiv</a>, og man siger at <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ϕ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \phi }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/72b1f30316670aee6270a28334bdf4f5072cdde4" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.385ex; height:2.509ex;" alt="{\displaystyle \phi }"></span> er en <b>bijektion</b>. En bijektiv afbildning afbilder således til ethvert element i <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Y}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>Y</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Y}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/961d67d6b454b4df2301ac571808a3538b3a6d3f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.171ex; width:1.773ex; height:2.009ex;" alt="{\displaystyle Y}"></span> ét (og kun ét) element i <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle X}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>X</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle X}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/68baa052181f707c662844a465bfeeb135e82bab" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.98ex; height:2.176ex;" alt="{\displaystyle X}"></span>; dvs. alle elementer i <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle X}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>X</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle X}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/68baa052181f707c662844a465bfeeb135e82bab" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.98ex; height:2.176ex;" alt="{\displaystyle X}"></span> og <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Y}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>Y</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Y}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/961d67d6b454b4df2301ac571808a3538b3a6d3f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.171ex; width:1.773ex; height:2.009ex;" alt="{\displaystyle Y}"></span> "er med" i afbildningen, og hverken den "forlæns" eller den "baglæns" afbildning afbilder til to elementer. </p><p>Bijektioner spiller en væsentlig rolle inde for alle grene af <a href="/wiki/Matematik" title="Matematik">matematikken</a>. Specielt er bijektionerne præcis de <a href="/w/index.php?title=Invertibel&action=edit&redlink=1" class="new" title="Invertibel (ikke skrevet endnu)">invertible</a> afbildninger. Altså findes til en bijektion <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi :X\to Y}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ϕ</mi> <mo>:</mo> <mi>X</mi> <mo stretchy="false">→</mo> <mi>Y</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \phi :X\to Y}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b98600ef34bb9c70ab402e2f46de411a750ca3ab" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:10.69ex; height:2.509ex;" alt="{\displaystyle \phi :X\to Y}"></span> en entydigt bestemt afbildning <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi ^{-1}:Y\to X}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msup> <mi>ϕ</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>−</mo> <mn>1</mn> </mrow> </msup> <mo>:</mo> <mi>Y</mi> <mo stretchy="false">→</mo> <mi>X</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \phi ^{-1}:Y\to X}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/1d3314a0321ba3ebbe2e41ff44403cd36223ac44" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:13.023ex; height:3.009ex;" alt="{\displaystyle \phi ^{-1}:Y\to X}"></span> sådan at <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi \circ \phi ^{-1}=\phi ^{-1}\circ \phi }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ϕ</mi> <mo>∘</mo> <msup> <mi>ϕ</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>−</mo> <mn>1</mn> </mrow> </msup> <mo>=</mo> <msup> <mi>ϕ</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>−</mo> <mn>1</mn> </mrow> </msup> <mo>∘</mo> <mi>ϕ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \phi \circ \phi ^{-1}=\phi ^{-1}\circ \phi }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0c00a7001df5ff5a831d67511c314e4fab19f77c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:17.695ex; height:3.009ex;" alt="{\displaystyle \phi \circ \phi ^{-1}=\phi ^{-1}\circ \phi }"></span>. Omvendt gælder, at hvis en afbildning <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ϕ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \phi }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/72b1f30316670aee6270a28334bdf4f5072cdde4" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.385ex; height:2.509ex;" alt="{\displaystyle \phi }"></span> har en <a href="/wiki/Invers" class="mw-disambig" title="Invers">invers</a>, da er <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ϕ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \phi }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/72b1f30316670aee6270a28334bdf4f5072cdde4" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.385ex; height:2.509ex;" alt="{\displaystyle \phi }"></span> bijektiv. </p><p>Bijektioner bruges bl.a. indenfor mængdelære, hvor to mængder, X og Y, har samme <a href="/wiki/Kardinalitet" title="Kardinalitet">kardinalitet</a>, hvis der findes en bijektion, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \phi :X\to Y}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ϕ</mi> <mo>:</mo> <mi>X</mi> <mo stretchy="false">→</mo> <mi>Y</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \phi :X\to Y}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b98600ef34bb9c70ab402e2f46de411a750ca3ab" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:10.69ex; height:2.509ex;" alt="{\displaystyle \phi :X\to Y}"></span>. </p> <div class="mw-heading mw-heading2"><h2 id="Se_også"><span id="Se_ogs.C3.A5"></span>Se også</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Bijektiv&veaction=edit&section=1" title="Redigér afsnit: Se også" class="mw-editsection-visualeditor"><span>redigér</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Bijektiv&action=edit&section=1" title="Edit section's source code: Se også"><span>rediger kildetekst</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Isomorfi" title="Isomorfi">Isomorfi</a></li></ul> <div style="clear:both; visibility:false; display:none"></div><table class="" style="width: 100%; float: none; margin: 0 auto; border-collapse: collapse; background: #FBFBFB; border: 1px solid #aaa; border-left: 10px solid #66bb77;padding: 0.25em 0.5em;"> <tbody><tr><td style="padding: 0.25em 0.5em;"><span class="metadata"><span typeof="mw:File"><a href="/wiki/Fil:Greek_lc_pi_icon.svg" class="mw-file-description" title="Matematik"><img alt="Matematik" src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Greek_lc_pi_icon.svg/28px-Greek_lc_pi_icon.svg.png" decoding="async" width="28" height="27" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Greek_lc_pi_icon.svg/42px-Greek_lc_pi_icon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Greek_lc_pi_icon.svg/56px-Greek_lc_pi_icon.svg.png 2x" data-file-width="100" data-file-height="96" /></a></span></span></td><td style="width:100%"><b>Spire</b><br /><div style="font-size:85%;line-height:135%;">Denne artikel om <a href="/wiki/Matematik" title="Matematik">matematik</a> er en <a href="/wiki/Hj%C3%A6lp:Stub" title="Hjælp:Stub">spire</a> som bør udbygges. 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