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Marks/Symbols at the end of solutions

  1. Mar 1, 2005 #1
    Does anyone know where I can find out what they mean. I'm just a curious person. I was able to look "qed" up, but I don't know how to look for the other symbols. Anyone know a website or just reply with the symbol and explanation, if you know. Cheers!

    Latin. quod erat demonstrandum (which was to be demonstrated).
  2. jcsd
  3. Mar 1, 2005 #2
    Symbols at the end of solutions are simply means of saying "proven" or "finished". It is a way of letting the reader know that you have reached the end of the proof and you have successfully demonstrated that the article in question has been proven to be true.

    It's really up to the author as to what character is used. Mostly now you see a solid block (especially in periodicals and journals), but QED is an old-school (and in my humble opinion, the most elegant) way of ending a proof. I've also seen "Math is phat!" and "So There!" at the end of informal proofs. :smile:
  4. Mar 1, 2005 #3


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  5. Mar 1, 2005 #4
  6. Mar 2, 2005 #5


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    You ought to read carefully

    "Does anyone know where I can find out what they mean. I'm just a curious person. I was able to look "qed" up, but I don't know how to look for the other symbols. Anyone know a website or just reply with the symbol and explanation, if you know. Cheers!"
  7. Mar 2, 2005 #6


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    QED also means Quantum Electrodynamics :) Something that Feynman developped
  8. Mar 2, 2005 #7


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    I'm going to start ending proofs with "Who's your daddy?" I wonder if it'll catch on. :rolleyes:
  9. Mar 2, 2005 #8


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    Then why did he share the prize with Sin-Itiro Tomonaga and Julian Schwinger?
  10. Mar 2, 2005 #9
    As should you, cronxeh, because you linked to a site which gives no more definition of what "QED" actually means than the OP originally included in his post. Your link only says that QED means "Quod Erat Demonstrandum (Latin: Which Was to Be Demonstrated)", which is exactly what the last line of the original post was.

    I don't wish to turn this into an argument over something so petty, however you shouldn't point fingers about someone's ability to read and interpret a question, or lack thereof, when your own input on the matter was lacking.
  11. Mar 2, 2005 #10


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    Honestly,Sin-Itiro Tomonaga discovered the (operatorial) formalism of QED in 1943,5 years b4 Schwinger.(Feynman is responsable for path-integral approach to QM & QED).But he was in Japan.And Japan was at war with the US.

  12. Mar 2, 2005 #11


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    Oh, but I insist:

    OP already stated what QED was - I was able to look "qed" up, but I don't know how to look for the other symbols.

    I gave him a link which he asked for - on the site that has over 398,000 acronyms, and definitions, contrary to your witty remark on how "elegant" QED remark is, and subsequent zero input on your behalf
  13. Mar 2, 2005 #12
    And so we've come to this. If the only measure of whether you have contributed to a thread or not is based solely on your ability to post a link to somone's work, and not trying to explain the situation yourself, then I suppose I'll do that as well:


    That link contains not only an indepth explanation on the meaning of what QED stands for and its history, it goes on to further supply what the OP asked for, which was some more symbols, and what they mean.

    Cronxeh, I have sent you a private message regarding this "discussion" - I was originally going to post it here, but I didn't want to further destroy an already ruined thread. If you still wish to maintain that you're right and I'm wrong, let's do this privately.

    Edit: my PM turned into a page-long letter. It's just not worth it for me to send it. Cronxeh, next time, stop before you deem somone's input worthless unless you're positive that you're helping. I happen to believe that my personal explanation does more to help than posting a link to an acronym finder that doesn't explain what the definitions actually mean. You obviously don't, so let's drop it and aggree to disaggree. If that's not good enough, I'm sure you'll let me know, and I'll get to use my letter after all.

    This is a forum made for people to help people. If we're meant to do so in a robotic, purely factual way, without injecting discussion and opinions (eg, which method I like the best), then we might as well shut the board down, since everyone can get their information from Google and Acronym Finders.
    Last edited: Mar 2, 2005
  14. Mar 2, 2005 #13


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    First, this is not a contest! I'm not in anyway concerned with how many posts a person makes but with whether he does or does not give a useful answer. Giving a link to a website that answers the question is an excellent answer- it is, in my opinion, better than taking up webspace by giving the same answer again.

    Cronex may have misunderstood the original post. He gave a link to a website that explains "qed" as well as other acronyms. He may not (or may) have understood that the original poster was wanted other symbols and ways of saying that a proof was done.

    I agree that this kind of back and forth "did not" "did so" is a waste. However, I also notice that it was scholzie how started it. Yes, it was, no doubt, an honest attempt to point out a mistake (Although I don't see how doing that would help. The mistake, if it was one, was already made.) but scholzie didn't need to respond to cronex's response!

    And I hereby declare that I will not respond any further on this thread!
  15. Mar 2, 2005 #14


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    I actually did this a few years back. The work was returned to me, along with a load of red pen about "Who's the daddy?" not being acceptable notation. Apparently, neither is "Get in!" or "Score!".
  16. Mar 2, 2005 #15


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    Well perhaps I shouldnt have blasted at you, scholzie - I've had better days

    As for a source for good links - to original poster:

    You can look up the meaning of an acronym at the website I posted before, then go to en.wikipedia.org

    Or if you not sure exactly what you looking for - try Google Suggest
    http://www.google.com/webhp?complete=1&hl=en And http://scholar.google.com/
    Last edited by a moderator: Apr 21, 2017
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