MSN: La Teoria della Relatività di Albert Einstein in soldoni: ecco come ha cambiato la Fisica
Dalla natura dello spazio-tempo alla comprensione della gravità, la Teoria della Relatività di Albert Einstein ha trasformato la Fisica e continua a influenzare le scoperte scientifiche. Un secolo ...
La Teoria della Relatività di Albert Einstein in soldoni: ecco come ha cambiato la Fisica
QED is short for the Latin phrase quod erat demonstrandum and means, loosely, "that which was to be shown". As noted in the comments, it's a summary way of saying that the proof is concluded.
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. Putting QED after that sentence was their way of saying, "and that's what I was trying to prove, so there, I've proved it". We aren't ...
0 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".
In math, proofs are often accompanied by 'QED' (quod erat demonstrandum) at the end, indicating their conclusion. Some authors use a square symbol ($\square$) instead of QED, with the same meaning....
It's just a phrase, so it should be used where appropriate. One "makes" or "does" a construction, and "proves" or "demonstrates" a theorem. So, QEF when a construction is finished, and QED when a proof is finished.