I’m currently writing my PhD thesis, in a mathematical field in physics. I have published a handful of papers, and the thesis is going to be mostly based on these results. I assume that, even though they are published, I should be including full proofs in the thesis.

I also assume I will effectively need to rewrite these proofs, if only for copyright reasons, having surrendered some of my rights to the journals in which these papers were published, and also for self-plagiarism reasons.

Is there anything I should look out for, and are my assumptions correct?

Some time ago I was approached by a fellow researcher that had an idea on an earlier work of mine. We started a collaboration and as a result we submitted a manuscript in a prestigious journal. Recently, I stumbled on a publication of my coauthor in which he had used almost verbatim a large part of our common submission (a page long). These parts include results which were entirely mine. I am really disappointed and I am not sure how to proceed with this.

For example, I want to propose a new algorithm for an existing problem, and I already have published several papers about this topic, they share exactly same background, is it OK for me to copy the “background” and “related work” part from my published paper?

The background contains some already well-studied techniques, in order for the paper to be self-containing, they should be briefly introduced (instead of just being cited).

I don’t see the meaning that I have to express the exact same thing in a different way for every new paper

I am currently writing my master thesis and I am also running a popular blog about my research area. Some people asked me about certain topics and if I could write about them on my blog to make them more understandable to newcomers in our field.

Now it is tempting for me to just copy parts of my yet uncompleted thesis and mash together into blog posts. This will help me to save time writing them (I usually do not have the time) and it will benefit others. However, I worry that people see that as self-plagiarism. In particular people on the thesis committee might say I copied parts of the thesis from the internet.

What would be the right way to save me from trouble here. Shall I cite my unpublished thesis, or should my thesis cite my blog posts? Should the blog posts have clear indications that I copied verbatim from my unpublished thesis? Will I get into trouble if people see that in my thesis I copied verbatim from my blog posts (if I cite my blog posts rather than the other way around).

Recently I received a plagiarism report on my accepted manuscript. It is highlighted that total 25% text appeared in other sources though they are cited properly.

When I checked the report, I found ~20% text appears in references only and another ~3% text is due to the use of a long phrase “The tropical cyclone wind speed climatology”. This phrase was actually very frequently used in one of my another paper. The rest ~2% text appears in introduction and methods. In methods, I had used some well known mathematical equations and related descriptions e.g. which variable denotes what.

So how to deal with this situation? How can I convince to the editor?