What to do about not receiving credit in a paper (lack of acknowledgment) Recently there have been a few instances of preprints I've seen on arXiv where I felt that I didn't receive due credit (an acknowledgment or at least a mention) for certain things. Here are a couple examples:


I mentioned a fact to a collaborator at a conference. It wasn't a deep, just an interesting construction that was surely bound to be useful in certain situations. A year or so later I see a paper by the collaborator on arxiv, where one section of the paper involves developing this construction and applying it (in ways that were certainly new to me). However I wasn't acknowledged or mentioned.
To another collaborator I wrote an email, with another construction and a formula that I expected it to satisfy with some strong evidence. Several months later I saw that the collaborator wrote a paper where the definition plays an almost central role and a version of the formula is proved. No acknowledgement again.


Basically my question is what is the best way for me to deal with situations like this? I am a young post doc recently out of Phd. I don’t like to be the one who wants credit for everything. However it does feel annoying when even close collaborators don’t have enough respect for me to not steal my ideas (ok, maybe that’s a harsh wording choice). But the core of it, now that I write this question, is really that I feel disrespected. Especially, since I tend to acknowledge people quite freely.  It’s obvious to me that if I was a senior and/or well-known mathematician, they wouldn’t have “forgotten” to acknowledge me.  The only options I can think of are:


ignore and move on. Don’t change my behavior, just learn to accept this accept of academia culture.
Ignore and move on. Be more protective of my ideas in the future. Be more proactive about writing down and publishing my ideas as soon as possible. Choose different people to collaborate with.
Confront the people in question and ask them to acknowledge me. I don’t like this option because I’m a non confrontational person. And I don’t want to damage good relationships. Also, i don’t want to get a reputation for being someone who asks people to credit him with things.


By my nature I’m leaning towards option 2. But it saddens me to realize how cynical I become since starting my Phd when I imagined the mathematics community to be so kind and generous.
In my opinion, aknowledgements are not important enough to get bothered about. Very few people would have even noticed the acknowledgement, and your career would not have been helped in any measurable way.

But at least in your second example, which was more more of an "idea for a paper" than a "helpful comment," I do consider it a breach of etiquette for your collaborator to write the paper himself without offering to involve you as a coauthor. Perhaps in the future, you could phrase such helpful emails as more explicit invitations to collaborate. That way you won't have to be stingy with your ideas, but you'll still get credit.