In my Bachelor's thesis, I implemented four new compression algorithms into a small Java library developed at my university (used only internally for teaching purposes). In my actual Bachelor's thesis (as in text), I described all implemented algorithms in sections: Analysis, Design, Implementation and Testing.

My question is regarding the Analysis section. In the beginning, I had a subsection called "Basic notions" where I defined basic terms used further in text. That included for example: symbol, alphabet, string, code, compression, compression algorithm, compression ratio, etc. It all summed up to about 3 pages. Everything was properly cited.

Now, I am continuing with my Master's thesis. I work on the same library and part of my task was to rework it from the perspective of data flow. Compared to my Bachelor's thesis, I did not implement new algorithms, part of my task was to focus on interfaces and data flow between those already implemented algorithms.

I am now writing the text and I want to define terms that I will need in the following sections. These terms are overlapping a lot with the section "Basic notions" that I had in my Bachelor's thesis.

My question is, how much if any at all, can I reuse from my Bachelor's thesis? Can I copy out what I need if I properly cite it as I did in my Bachelor's thesis (as I won't cite my own Bachelor's thesis, but I will cite books and papers I originally cited in my Bachelor's thesis)?

1 Answer 1


I'll assume that you bachelor's thesis was "published" in some form, even if only by your university. As such, it is an existing work that should be cited, and can be used, like any other work.

I'll also assume that you didn't give up copyright to the original, though you might have if it was formally published. If you hold copyright, then you can copy longer sections of it (with citation) than you can if it is the work of another.

But, the ideas in the original are free to use, by yourself or anyone else. So, you can capitalize on your libraries, and such.

Just don't copy verbatim or even paraphrase without citation. You can, however, do something like citing the early work for a long section of the original, probably paraphrasing, without specifically citing each statement. As long as it is clear you aren't self plagiarizing.

Note that the purpose of prohibitions against self plagiarizing are a subset of the prohibitions agains plagiarizing others. A researcher, reading the later work, wants a link to the early work so that they can get the full context of the new work, including those things that were only written in the early one. You can't "steal ideas" from yourself, but you need to keep the chain of context unbroken.

Note, also, that, with the exception of quoting longer passages, others can do the same thing and need to follow the same rules. Cite what you use and make it clear what is new and what is derived.

Your advisor will probably give good advice about the limitations on how much you can quote. Paragraphs might be fine. Pages might raise questions and probably should. For someone else, paragraphs might be too much, but that is a copyright issue, not a plagiarism one, as long as citations are made.

  • Thank you for your explanation. To my knowledge, I hold the copyright claim, but my faculty can use my thesis for teaching and research purposes however they want. That is the default at my faculty, other options had to be approved by the dean.
    – johny
    Nov 7, 2021 at 14:33
  • 1
    Unless you have formally signed away copyright it is yours. Likely they are assuming that they have a perpetual license to use the work of students. And for joint work (professor as co-author), you jointly hold the copyright. But it might be worth checking with the dean to see what they are really assuming. But, even if they claim copyright, you can still use the work. The only restriction is on how much you can properly quote. The copyright is about the expression, not the ideas.
    – Buffy
    Nov 7, 2021 at 14:35
  • Thank you for finding the time and explaining this to me.
    – johny
    Nov 7, 2021 at 17:29
  • I'd argue it benefits no one for sections on notation to be as much as paraphrased just for the sake of it (although it might be helpful to re-read them and consider whether some changes are warranted), but this is exactly a kind of thing to be cleared with the committee. Many would prefer for the work to be self-contained to an extent an expert in the field does not have to follow the citations to understand the thesis, and some would yet require these introductory sections to be completely rewritten. It may feel like a pointless torture so am personally very against this practice, YMMV :)
    – Lodinn
    Nov 8, 2021 at 11:25

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