Saying QED in different languages
I was wondering whether it would be easy to know how to say “QED” in whatever language I could think of… Well, it seems (not so unexpectedly after all) that Wikipedia was the right tool to use : so starting from the QED article (not the quantum electrodynamics one !) of the English Wikipedia, the language list allows to switch to the version of the same article in many other idioms ! Ever wondered how Icelanders ended their proofs ?
From this investigation it comes out that
- in English, as you probably know, the phrase QED, for quod erat demonstrandum is used, following the tradition of Latin-speaking (or rather Latin-writing) mathematicians. I guess that people used to write mathematics in Latin for quite a long time, maybe even quite recently. It seems that many people, not only English-speaking still use it, even though it was wiped out by generalised use of LaTeX and the ∎ (U+220E) symbol.
- in French, we say ce qu’il fallait démontrer (CQFD), which is nothing more than the exact translation, while Italian-speaking mathematicians are supposed to use come volevasi dimostrare: it would be nice to check old Italian works (maybe by Bianchi, Castelnuovo…) to find occurrences
- ancient Greek mathematicians are said to write ὅπερ ἔδει δεῖξαι which if I am not misled means what was to be shown; it seems that Modern Greek kept the acronym, as you can see in the (very valuable) lecture notes of the university of Crete.
- in German, the abbreviation is w.z.b.w., meaning was zu beweisen war, which is still the same phrase, and have declinations in Dutch wat te bewijzen was, and Luxemburgese wat ze beweise war (I must say I didn’t expect the Luxemburgese wikipedia to have an article on this, but there is a nonzero number of Luxemburgese students in mathematics)
- the English article says the Russian equivalent is ч.т.д. for что и требовалось доказать : I wonder if доказать is based on the same root as δείκνυμι
- the Icelandic article is titled það sem sanna átti: I have no clue how to recognize a translation of QED here, except maybe það means that and átti should maybe be a form of the verb to be
- there is also an Estonian article talking about mikä oli todistettava, but I would be curious to know how it translates into Finnish
- continuing with Baltic countries, the Latvian article states that QED translates into kas bija jāpierāda
- last but not least, the Arabic article is entitled وهو المطلوب إثباته: my dictionary says مطلوب is the past participle of a verb meaning ask, require, and a little handwaving makes me say it means “which was asked for a proof”
For more completeness I am still missing the Hungarian, Chinese and Japanese version of QED…