Last year, I went to a math conference to present new results in my paper 1, which was just submitted to a journal. Afterwards, a well-known Professor X approached me to discuss the paper. He seemed very interested in the results, and mentioned paper 2, which was written by him and his collaborators. He didn’t ask me to cite his paper though (in hindsight, I guessed that he mentioned it just because he wanted it to be cited).
Recently, I asked him for a letter of recommendation. Initially, he agreed. However, after one month, he sent an email saying that he changed his mind, and criticized me for not citing his paper 2 in my paper 1, which is now published.
I already have enough references so his refusal doesn’t cause any harm. However, I wonder if I should apologise to him for not citing his paper?
The overlap of the two papers is as follows. My paper 1 has two main ingredients A and B, which are equally important. His paper 2 has two main ingredients A and C. I didn’t know about his paper until he told me, and thus I didn’t use any ideas or results of his paper.
- When I talked about the main ingredients, I meant the overall paper, not the new results. Our paper didn’t have any overlap results. The part A was about the physical model (already well-established and in textbooks), which was our starting point. Our paths then diverged from this common physical model.
- I removed some references and an appendix to meet the page requirement, including this professor's paper and some other textbooks that described the physical model. We deliberately chose the least relevant ones to remove, and we didn't remove anything that would lead to plagiarism issues.
- As a side note, a senior colleague Y just showed me a paper 3, written by Y 5 years before paper 2, but Professor X didn't cite paper 3 in paper 2, even though they had similar mathematical results!