Definition:QED
Definition
The initials of Quod Erat Demonstrandum, which is Latin for which was to be demonstrated.
These initials were traditionally added to the end of a proof, after the last line which is supposed to contain the statement that was to be proved.
The usage is considered hopelessly old-fashioned nowadays, and is rarely seen outside nerd sitcoms.
The Halmos symbol $\blacksquare$ is usually used instead.
$\mathsf{Pr} \infty \mathsf{fWiki}$ universally uses $\blacksquare$ to signify the end of a proof.
The symbol $\Box$ is used to signify the end of a stage part way through a proof, where a subsidiary result is proved.
Also known as
Some sources render it as Q.E.D. (that is, with dots).
Internationalization
Q.E.D. is translated:
In Afrikaans: | W.B.M.W. | (that is: wat bewys moes word) | ||
In Armenian: | Ի.Է.Պ.Ա. | (that is: Ինչ էլ պահանջվում եր ապացուցել) | ||
In Bengali: | অতঃ সিদ্ধ | (that is: ataha siddha) | ||
In Bulgarian: | К.Т.Д. | (that is: което трябваше да се докаже) | Pronounced: koeto tryabvashe da se dokazhe | |
In Catalan: | C.V.D. | (that is: com volíem demostrar) | ||
In Czech: | C.B.D. | (that is: což bylo dokázati) | ||
In Danish: | H.S.B. | (that is: hvilket skulle bevises) | ||
In Dutch: | W.T.B.W. | (that is: wat te bewijzen was) | ||
In Esperanto: | k.e.d. | (that is: kio estis demonstrenda) | ||
In Estonian: | M.O.T.T. | (that is: mida oligi tarvis tõestada) | ||
In Finnish: | M.O.T. | (that is: mikä oli todistettava) | ||
In French: | C.Q.F.D. | (that is: ce qu'il fallait démontrer) | ||
In Georgian: | რ.დ.გ. | (that is: რისი დამტკიცებაც გვინდოდა) | Pronounced: risi damtkic'ebac' gvindoda | |
In German: | w.z.b.w. | (that is: was zu beweisen war) | ||
In Greek: | ο.ε.δ. | (that is: ὅπερ ἔδει δεῖξαι) | Pronounced: oper edei deixai | |
In Gujarati: | ઇતિ સિદ્ધમ્ | (that is: iti siddham) | ||
In Hindi: | इति सिद्धम् | (that is: iti siddham) | ||
In Hebrew: | מש"ל | (that is: מה שצריך להוכיח) | Pronounced: mah shetzarich l'hochiach | |
In Hungarian: | E.K.B. | (that is: ezt kellett bizonyítani) | ||
In Icelandic: | þ.s.s.á. | (that is: það sem sanna átti) | ||
In Irish: | R.B.T | (that is: an rud a bhí le taispéaint) | ||
In Italian: | C.V.D. | (that is: come volevasi dimostrare) | ||
In Japanese: | 結論 | (that is: ketsuron) | ||
In Kannada: | ಇತಿ ಸಿದ್ಧಮ್ | (that is: iti siddham) | ||
In Latvian: | k.b.j. | (that is: kas bija jāpierāda) | ||
In Lithuanian: | k.r.į. | (that is: ką ir reikėjo įrodyti) | ||
In Marathi: | इति सिद्धम् | (that is: iti siddham) | ||
In Polish: | c.b.d.u. | (that is: co było do udowodnienia) | ||
In Portuguese: | C.Q.D. | (that is: como queríamos demonstrar) | ||
In Romanian: | C.C.T.D. | (that is: ceea ce trebuia demonstrat) | ||
In Russian: | ч.т.д. | (that is: что и требовалось доказать) | Pronounced: shto ee tryebovalos dokazat | |
In Sanskrit: | इति सिद्धम् | (that is: iti siddham) | ||
In Serbian: | ш.т.д. | (that is: што је и требало доказати) | Pronounced: shto ye ee trebalo dokazati | |
In Slovak: | Č.B.T.D. | (that is: čo bolo treba dokázať) | ||
In Spanish: | Q.E.D. | (that is: queda entonces demostrado) | ||
In Swedish: | VSB | (that is: vilket skulle bevisas) | ||
In Telugu: | ఇతి సిద్ధమ్ | (that is: iti siddham) | ||
In Thai: | ซ.ต.พ. | (that is: ซึ่งต้องพิสูจน์) | ||
In Ukrainian: | щ.в.д. | (that is: що і вимагалося довести) | Pronounced: shcho ee veemagalosya dovestee | |
In Vietnamese: | đpcm. | (that is: Điều phải chứng minh) |
Technical Note
In order to render $\blacksquare$, use the template {{qed}}
.
In order to render $\Box$, use the template {{qed|lemma}}
.
When {{qed}}
is used, it automatically adds the page on which it is implemented to Category:Proven Results.
Sources
- 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): QED
- 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): quod erat demonstrandum
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): QED
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): QED
- 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): QED
- 2021: Richard Earl and James Nicholson: The Concise Oxford Dictionary of Mathematics (6th ed.) ... (previous) ... (next): QED