Q.E.D.

QED English 2020 January 24 Etymology From en la-lat QED, from en la quod erat demonstrandum.Q.E.D. int. and n.1 yes 240240 December 2007 yes; abbrev Pronunciation en /ˌkjuːiːˈdiː/ RP en En-uk-QED.oga RP en /ˌkjuˌiˈdi/ GA Phrase phr en mathematics en mathematics dated en quod erat demonstrandum what was to be proved; what was to be demonstrated: placed at the end of a mathematical proof to show that the theorem under discussion is proved. en Mr. Ash A New and Easy Way of Demonstrating Some Propositions in Euclid Philosophical Transactions: Giving Some Accompt of the Present Undertakings, Studies and Labours of the Ingenious in Many Considerable Parts of the World London Printed by T. R. for John Martyn, printer to the Royal Society; at the Bell in St. Pauls Church-Yard. 20 August 1684 XIV 162 674 https://books.google.com/books?id=wvwSuBLY6GgC&pg=RA1-PA674 630046584 [A]fter the same manner S and U are proved to be equal, therefore the square of CB is equal to the square of the 2 other sides Q E D. en The Mathematical Repository, Nº 63 The Gentleman’s Diary, or The Mathematical Repository; an Almanack for the Year of Our Lord 1803:Being the Seventh after Bissextile. Containing Many Useful and Entertaining Particulars, peculiarly Adapted to the Ingenious Gentlemen Engaged in the Study and Practice of the Mathematicks. The Sixty-third Almanack Published of this Kind; and the Fifty-first of the New Style in England. London Printed for the Company of Stationers by Nichols and Son,Red Lion Passage, Fleet-street.; [a]nd sold by George Greenhill,Treasurer to the Company, at their Hall, Ludgate-Street. 1803 33 https://books.google.com/books?id=pyMsAAAAMAAJ&pg=PA33 225667331 Now let any right line meet four harmonicals in , , , , and if those harmonicals be parallel, the thing is evident; but, if they intersect in , draw parallel to , the line most remote from ; then, by the first part, , and or . Therefore . q. e. d. en William Dunham Euler and Analytic Number Theory Euler: The Master of Us All The Dolciani Mathematical Expositions 22 [Washington, D.C.] w:Mathematical Association of America 1999 64 https://books.google.com/books?id=x7p4tCPPuXoC&pg=PA64 978-0-88385-328-3 By Cases 1 and 2, we see that any finite collection of primes cannot contain all such primes. Thus there are infinitely many primes of this type. ¶ Q.E.D. en extended use outside mathematics en by extension Used to indicate that an argument or proposition is proved by the existence of some fact or scenario. I IV 42 That this part of the world has actually been peopled (Q. E. D.) to support which, we have living proofs in the numerous tribes of Indians that inhabit it. en Benedict de Spinoza [i.e., Baruch Spinoza]; R[obert] Willis [The Ethics.] Part I.—Of God. Benedict de Spinoza; His Life, Correspondence, and Ethics London Trübner & Co.,60, Paternoster Row. 1870 418 https://books.google.com/books?id=isIwAAAAYAAJ&pg=PA418 1021877894 PROP[OSITION] VI. One substance cannot be produced by another substance. ¶ Demonst[ration]. In the preceding proposition we have seen that there cannot in the nature of things be two Substances of the same attribute, or that they have anything in common (by Prop. II.); and so (by Prop. III.) one cannot be the cause of, or be produced by, another: q. e. d. en C. H. Claudy Tanks Frank V. Chambers The Camera: An Illustrated Magazine Devoted to the Advancement of Photography Philadelphia, Pa. The Camera Publishing Company July 1908 12 7 252 https://books.google.com/books?id=KDQyAQAAMAAJ&pg=PA252 Of all those on the market, Eastman's is the only one with a solution tight, locking cover. ¶ Q. E. D. Usage notes When used to end a mathematical proof, QED is somewhat dated or traditional; modern textbooks often use the graphical symbol ∎ (the halmos or tombstone) instead. Other languages generally use a vernacular abbreviation, such as fr CQFD ce qu'il fallait démontrer or pt C.Q.D. como queríamos demonstrar. Alternative forms en QED Q. E. D. q. e. d. q.e.d. Related terms en QEF Translations initialism placed at the end of a mathematical proof to show that the theorem under discussion is proved quod erat demonstrandum Aramaic: arc קמ׳׳ל qa mashma' lan Chinese: Mandarin: cmn 證畢 zhèngbì, cmn 證訖 zhèngqì, cmn 得證 dézhèng Czech: cs c.b.d. Esperanto: eo KEP Estonian: et m.o.t.t MOTT Finnish: fi MOT French: fr CQFD Georgian: ka რ.დ.გ German: de w. z. b. w. Alemannic German: gsw h.x. humorous, informal, uncommon Greek: el Ό.Έ.Δ. Hebrew: he מָשָׁ"ל masha"l, he מ.ש.ל. m-p m.sh.l. Hindi: hi इ. सि. Icelandic: is þ.s.s.á. Italian: it CVD Polish: pl c.b.d.o., pl c.b.d.u., pl cnd., pl ckd. Portuguese: pt CQD, pt QED Russian: ru ч. т. д. Slovak: sk Č.B.T.D. Spanish: es C.Q.D. Swedish: sv VSV, sv VSB Vietnamese: vi đpcm Noun A certain fact or scenario that proves an argument or proposition; a justification. en Ouida [pseudonym; Maria Louise Ramé] The General’s Match-making; or, Coaches and Cousinship Cecil Castlemaine’s Gage, and Other Novelettes London Chapman and Hall,193, Piccadilly 1867 233 https://books.google.com/books?id=50RWAAAAcAAJ&pg=PA233 35980974 We all go in for the dolce here except you, and you're such a patent machine for turning out Q.E.D.s by the dozen, that you can no more help working than the bedmaker can help taking my tea and saying the cat did it, en Nina Melville The Theatre V[ictor] F[rancis] Calverton [pseudonym; George Goetz] The Modern Monthly: An Independent Journal of Radical Opinion April 1936 IX 9 27 https://books.google.com/books?id=RoweAQAAMAAJ&pg=PA27 1 4756578 The same thing, I believe, that was lacking in Let Freedom Ring—lack of dramatic integration, lack of dramatic intensity, lack of all those elements, call them what you will, which make a play a play and not a tract, and certainly not a Q.E.D. thesis. Alternative forms en QED Translations fact or scenario that proves an argument or proposition justification References Further reading Anagrams en deq DEQ