2015年2月19日 · It's an abbreviation of quod erat demonstrandum, which is the Latin translation of a Greek phrase meaning "which had to be proven". To the ancient Greeks, a proof wasn't complete unless the last sentence in your proof was basically the statement of the theorem.

2019年5月31日 · As you know “QED” means “quod erat demonstrandum”, that is “what was to be shown”. It makes proofs more readable. Modern textbooks often conclude proofs with “which concludes the proof” or “which proves the assertion” or something. It’s the same thing, “QED” and the square are just convenient shorthands. $\endgroup$ –

2017年4月21日 · I had always used QED (quod erat demonstrandum) at the end of a proof until I was introduced to using Halmos' symbol. Since it was a 4-sided symbol, my mind has always associated this "quad" symbol with "quod".

2022年10月26日 · It is not accurate to say that symbol $\square$ has the same meaning as QED. It is simply a marker for the end of a proof, while QED is an actual statement that the proof is complete. It is simply a marker for the end of a proof, while QED is an actual statement that the proof is complete.

2014年10月7日 · While researching the term Q.E.D last night, the phrase Q.E.F was mentioned, which was apparently "used by Euclid to indicate the end of the justification of a construction". Does Q.E.F indicate the

2016年10月21日 · This Wikipedia page has an interesting discussion of the ways that QED has been translated into different languages (interestingly, not including English). I have seen other symbols used. This paper (which is famously the only PhD thesis in mathematics written by an NFL player) uses a white square with a vertical line going through it.

2023年12月12日 · Most propositions either end with "QED" or with "QEF", when the first one is used for proving propositions that are not constructions and the second one is for constructions. However, in Heath's translation, the first three propositions (in book one) don't end with "QED" or "QEF", but with "Being what it was required to do".

2011年11月20日 · Many symbols in math don't have a single meaning; and in fact this is not quite mathematics, but rather the use of a symbol as a shorthand, among mathematicians, for what would otherwise be an ordinary statement in one's language.

2020年10月16日 · Meaning of almost surely nonnegative. Ask Question Asked 4 years, ... – QED. Commented Oct 16, 2020 at 17:38

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