I am writing a mathematical paper. Since my English is not perfect, i am borrowing sentences from English-speaking authors. I have some questions about copy and paste from other papers to my paper. As you know, one needs some definitions and theorems from other papers. I cited all of papers that i used either definition or theorems from them.

1)Can i copy and paste the original either theorems or definition from the papers to my paper or i have to change them?i mean writing somehow that is not as same as original one. Because i have seen English-speaking authors often change original theorem or definition in their papers. On the other hand, i have seen someone does not.

2)As i mentioned, i am borrowing sentences from English-speaking authors. When i look it my introduction, i see this sentence from that paper, that sentence from that paper and ... It makes scene. My supervisor read it and he said it is okay( it is not ambiguous) but i'm scared that referee rejects my paper.

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    I take a somewhat hard line on this: usually lifting whole sentences from other people's papers is, in my view, plagiarism. Not the worst kind, but plagiarism nonetheless. However, this does not apply to statements of standard definitions (e.g. what it means for a group to be residually finite, etc.) but more to sentences where some opinion or insight is being stated
    – Yemon Choi
    Commented Sep 13, 2019 at 0:23
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    In particular, I do not think it is appropriate to construct your introduction as a collage of sentences from other people's work. You should try to communicate in your own words what it is that you think your paper is about, and why it might be interesting, not why Professor X thinks it is interesting
    – Yemon Choi
    Commented Sep 13, 2019 at 0:25
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    (This question, and the answers to it, may also be relevant academia.stackexchange.com/questions/20414 )
    – Yemon Choi
    Commented Sep 13, 2019 at 0:27
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    One possible concern, as well as the plagiarism, is that if your paper can be described by taking the intro from other's papers then your paper material has already been covered and it does not add much...
    – Solar Mike
    Commented Sep 13, 2019 at 5:03

3 Answers 3


Please do not borrow sentences

Instead, borrow sentence structures. If the original sentence is, "Our results also have implications on the study of öhkömönkiäiset.", you might write "Our main result also has implications on öhkömönkiäis-studies."

First, this way you are not copy-pasting. Second, this forces you to think about the language and therefore learn it, thereby reducing the need to copy and making writing a lot easier.

Also, go ahead and improve your English. There are many free resources online, but simply reading a lot is a great help. For more specific advice on how to learn the language, https://languagelearning.stackexchange.com/ is a fine place to ask. For specific questions about the English language, maybe ask at https://ell.stackexchange.com/.

(The easiest improvement to the English in this question would be to capitalize "I".)

Quoting definitions and theorems word-for-word

For many basic definitions, there are only a small number of ways of writing them clearly and compactly. Just use an established way of writing.

Sometimes, if a definition or result is complex or not yet established, there are better and worse ways of writing it and maybe even several variations that define slightly different things. In this case, cite the source, since the exact definition matters.

Usually you are somewhere between these two cases, in which case I would recommend you to write the definition or theorem by yourself, so that you are more likely to write it in the same way as your other results and to use the same notation.

  • Thank you for your good advice. I did it, but you can not do it for some theorems, because Authors write very short.
    – Michal
    Commented Sep 14, 2019 at 12:17
  • I have another question. what about same notation? because in mathematics it's not common to use some different notations.
    – Michal
    Commented Sep 14, 2019 at 12:26
  • @Michal If the definition is very short and standard, just use it. If it not standard, use it and refer to the source. Feel free to use the same notation; if there are several alternatives, maybe write something like "We use the same notation as~\cite{source}.", if the notation comes from a book or a significant paper.
    – Tommi
    Commented Sep 14, 2019 at 14:07

I am sympathetic to the problems in writing effectively in languages other than one's most native language.

Still, you should never just copy-and-paste. Period.

Nevertheless, yes, if/when you know well-enough some standard definitions/concepts, you will appreciate their highly optimized forms, and see that it is best to essentially say the same thing.

Yes. But don't "say the same thing" by copying-and-pasting. It should be that "the same thing" is what you yourself say, simply as the optimized description of the thing.

If the optimization is recent, yes, cite. If the optimization is 50 years old, and the idea is universal in your milieu, don't cite, unless you are making historical points.

Summary: never copy and paste, in any case.

  • "you should never just copy-and-paste" - +1. It's just bad practice. Commented Sep 14, 2019 at 0:06
  • Thank you. I am trying to do as much as i can. But, some Authors write as less as they can, so i can not optimize them.
    – Michal
    Commented Sep 14, 2019 at 12:19
  • I have another question. what about same notation? because in mathematics it's not common to use some different notations.
    – Michal
    Commented Sep 14, 2019 at 12:26
  • Always use standard notation, yes. Commented Sep 14, 2019 at 16:06

There is nothing wrong with something like: 'blah' was defined by R A Fisher [reference] as 'blah blah blah', in this paper we adopt that definition. - You give credit to the author of the definition, you do not give the impression that it was your idea.

If the definition is very well known in your field you might get away with 'blah' is usually defined as 'blah blah blah', but only if that is actually true.

Or you could equally justifiably say, 'we have restated Fisher's definition of 'blah' as 'blah blah halb' to take account of ...'

But there is something very wrong with: The definition of 'blah' is 'blah blah blah'. - You give the impression that you thought up that definition when in fact you just copied it.

The simple question to keep in mind is: if I wrote that, would the reader assume that it was my own work? If it isn't your own work then don't write it in a way that might mislead a reader into believing that it is.

  • Thank you for your advice. I'll do it. I have another question, what about notations? if i use same notation.
    – Michal
    Commented Sep 14, 2019 at 12:21

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