As a Ph.D. student, I am curious about the following: if you collaborate with a researcher(not necessarily your advisor) while being a student, should you write in your dissertation the work of the other collaborator?

Assume that while being a student, you collaborate with Prof. X, and you write a paper together. In this paper, the work was split 50-50, so that half of the results belong to Prof. X.

What should you do when writing your dissertation? Most probably, omitting the results of Prof. X will result in a significant gap in the thesis. I am particularly interested in the case of mathematics: if I cite the result, should I give a proof?

  • You should definitely discuss with Prof. X what you can include in your thesis and how to present things.
    – silvado
    Mar 22, 2018 at 7:53
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    "the work was split 50-50, so that half of the results belong to Prof. X." This isn't how it works. First of all, the results don't "belong" to anyone. Second of all, as you are coauthors, the credit for the results is jointly for you and the prof.
    – user9646
    Mar 22, 2018 at 8:22
  • As with many things, you need to ask your advisor. My department had a rule of maximum one coauthored chapter, but my advisor had a rule of zero coauthored chapters :/
    – Dawn
    Mar 22, 2018 at 14:08

6 Answers 6


I had a similar situation in my thesis, in math. The third chapter was based on a work that was jointly done with another researcher, a professor from another university. (In the end the paper we published was even with two other researchers, as we decided to join our efforts.)

  1. I had to ask the researcher for permission to include our joint results. This is a no-brainer (though of course he was happy to let me do it). When I sent out the thesis to my committee (of which he was part), I also sent him a copy beforehand and asked him if he was okay with what I had written, as they were his results too and he might want to check that I didn't mangle them before releasing them into the wild. My advisor also was on board from the start, but I imagine that you have to ask for permission if this isn't the case.

  2. I had to include acknowledgments for this in my thesis. Basically, I wrote a paragraph at the beginning of the chapter, stating "this chapter is based on joint work with [...]". Again, this is a no-brainer. I cannot claim all the results are due to me if they aren't. However, I didn't say anything of the sort "I did X% of the work and the other researcher did (100-X)% of the work", this isn't how it works, and it would have been in rather poor taste. At least in mathematics, it's expected that co-authors contribute roughly the same amount of work to a joint paper, but it's not an exact "50-50" (or 33-33-33, or 25-25-25-25...) distribution.

  3. The whole thesis had to be written by me, in my own words, including the results and the proofs that were actually due to the other professor. Moreover, I obviously had to perfectly understand, and be able to explain, and defend, all the results, as if they were mine.

All of this was explained to me by my advisor. It's possible that regulations in your university say something different. The essential part, I believe, which is only hinted at in the steps above, is to ask your advisor what to do exactly.

  • 6
    +1 but with the small caveat that it is my strong belief that permission for such a case is implied; or at the very least, it cannot be refused: the results are part of your thesis work, they belong in the thesis. Mar 22, 2018 at 12:43
  • 3
    @KonradRudolph Of course. It should be pretty much obvious for the other researcher that if you collaborate on something with a PhD student, then it's probably going to end up in the thesis. Still, I think it's courteous to simply ask.
    – user9646
    Mar 22, 2018 at 12:54
  • Were the joint results already published? If so, you don't need permission to cite the published work. Mar 23, 2018 at 4:19
  • @MichaelHardy They weren't published yet (it's a long story...).
    – user9646
    Mar 23, 2018 at 8:49
  • This answer reflects what I've seen, except for one thesis that gave the "X% and (100-X)%" details. This level of detail might even have been required by the university. And I'd add that, in addition to asking your adviser, you should also check any official rules of your university and your department. An adviser ought to know these and take them into account, but "ought to" isn't the same as "does", especially if universities or departments change their rules without notifying the faculty. May 18, 2019 at 0:05

It is completely normal to include in your thesis work that was done in collaboration. Almost every PhD thesis in STEM subjects includes at least some collaborative work, simply because your PhD itself is a collaboration between you and your advisor.

Usually, you just need to clearly state what work in your thesis was done in collaboration and with whom. It may also be expected that joint work should be put in your own words, rather than just copied from the paper. That's good practice anyway, since it's a great way to make sure you really understand the work. And you'll need to understand it because you can be examined on anything that's in your thesis.

Check your individual university's regulations for the precise details. And ask your advisor – this stuff is literally their job.

Assume that while being a student, you collaborate with Prof. X, and you write a paper together. In this paper, the work was split 50-50, so that half of the results belong to Prof. X.

That simply isn't how collaboration works in mathematics. The results "belong to" all the authors, because they came from a creative process that heavily involved all of them. Of course, some parts of the work will be solely by one person sitting in their office with a cup of coffee until they figure it out on their own, but it's mostly not like that. And usually, even these "solo results" receive at least some contributions from the other authors as the paper gets written and rewritten. And, very often, even if it was Author A who came up with the actual proof, Authors B and C were part of the process that led to that particular technique being chosen, and so on.

Of course, there are some exceptions. Sometimes, an author joins a collaboration late because their expertise on some area is needed. In computer science, papers are often released first as a shortened conference version (which is a peer-reviewed publication, unlike in mathematics) and later, the full version appears in a journal. I'm aware of papers where extra authors have been added to the journal version because of specific contributions they made after the conference. I guess the closest analogue in mathematics would be a paper going up on the ArXiv and then acquiring extra authors. If an author in that situation was a PhD student, I'd expect their thesis to include only a high-level summary of the material that existed before they joined the project.

The fundamental rule is honesty. If you can put your hand on your heart and say that you made significant contributions to the work and you're clear about who else contributed, it's almost certainly fine. If you're including big chunks of stuff that you made no significant contribution to, I'd hope you already know that it's wrong to say "I did this."


The short answer: Yes. However, it may depend on several details. In my case, I did include results from a collaborator in my thesis and that was generally accepted. I was however asked to provide an acknowledgement section where I had to clarify which results were done by me and which by the collaborator. Also, my thesis was in organic chemistry so things might be different in mathematics. So while I can't say if it is common or not in mathematics, I can tell you that it was allowed in my case.


In addition to the accurate answers so far, it's worth pointing out that the order of the author list matters in some fields: The first author is generally assumed to be the lead author, that is, the author who contributed most. In these fields it can be the case that lead authorship is required for claiming a paper for your PhD thesis.

Details may depend on the institution. For example, at the institution where I did my PhD, the regulations explicitely required three papers with me as the lead author for a cumulative PhD. A colleague of mine, who collaborated in a group where authors were always listed alphabetically, had a statement in his thesis where he assured that he was the de-facto lead author of his papers.

  • 1
    OP is in math. In (pure) math the author list is almost always alphabetical. And I say "almost" because I'm a mathematician and I like to be precise with quantifiers. In my big bibtex file with all the papers I've read, referenced, downloaded for later reading, or just because I liked the title... I think there are two papers with a non-alphabetical order out of almost a thousand. The first because the author whose name is first in the alphabet only wrote an appendix to the paper. The second is in applied math.
    – user9646
    Mar 22, 2018 at 12:56
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    @NajibIdrissi You're right, my answer is probably not relevant for the OP. It may be relevant for users who have the same question, but are from a different field. Mar 23, 2018 at 9:06

In our country, the Higher Education Commission requires a student to publish at least one paper in any well-reputed journal (IMPACT FACTOR or MASTER LIST JOURNAL) with lead authorship. However, there is no such restriction on including papers into thesis with multiple contributors.

In my personal opinion, I humbly suggest that a written consent of the co-authors should be obtained. To me, it sounds good both ethically and to be on a safer side. Also, the rules of the university matters, if they are silent then go ahead but atleast get a written consent of the co-authors for dealing with any possible future issues.

Hope this helps

-- Rocky


The instructions when I did my thesis were to just be clear about contributions from other people. I had 5 or 6 pieces and really 3 of them needed to fit together like a triangle. One of those 3 was mostly done by a visiting summer scholar. I got him started and did some measurements, but he took his "triangle leg" and drove it himself.

I always considered it part of my original domain so I wanted it in there. Plus you would have had a logical content gap if you omitted it. I just wrote a sentence or two paragraph (in italics, in main text) at the front of the relevant chapter. I think this was adequate. Being upfront and explanatory. But didn't require some long, precise allocation of every detail. Just the basic explanation that I gave you here. There was still "plenty of work" where I was the main driver so it was not an issue.

We had already co-published the "triangle leg" separately as a regular journal article. Visiting scholar taken care of (put as first author of that leg).

It is very normal that people work in collaborations (especially in experimental science) and that different students need to write up their theses in addition to regular journal articles. Just be upfront about what you did (don't say you fabricated samples if you did measurements or visa versa).

I am not used to some big signoff from the collaborators. They just wish you well. It is a good touch to give them a copy of the thesis (electronic or spiral bound, bound volume not required) so that they can learn from it, benefit from it, retain it for insights for themselves. Sometimes theses go into a bit more detail or are better explanations than terse journal reports.

If you are STILL worried, just notify him of your plans (going to have our collaboration as chapter 3, will credit you). Collaborator can squawk if he wants. (Unlikely, he will wish you well instead.) Uh...just don't try to get him to help you write thesis or the like...it's your glorified term paper, not his school assignment. He will be journal article driven.

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