I wrote a research paper and just realized that my idea has been published before. Must I cite? I work as an engineer in industry. I have been working alone in a project of my firm for four months. In the course of this, I invented a technique which can optimize and reduce considerably the cost for my firm.
The R&amp;D manager said my work is original, he hasn't seen it before. Therefore, my work will be presented to the director of my firm in the committee meeting next month, and he agreed with me that I can publish my work.
Yesterday, when I made some verification of citation sources, I found a thesis, published in December 2016 with the same idea as mine.
I made up this technique on my own, and I have never known this thesis before. But the key idea is already published in the thesis.
I understand now that I can no longer publish my technique. Even if I find my technique is actually more general and seems better than the technique in this thesis, it is not sufficient to publish unless I make more improvement.
Must I cite?


Yes, you must cite the thesis, since it's part of an author's responsibility to give an accurate representation of the state of the art.


  I understand now that I can no longer publish my technique


I think these worries might be unjustified. Most research is incremental, in the sense that it improves on existing work, rather than inventing something completely new. Just cite the work and clearly discuss (or even better, show experimental evidence) why your technique gives an improvement in terms of generality and speed.