Public personal ideas: using contributions from other people Let's say I'm thinking about an unsolved mathematical problem for a hobby and I draw some conclusions of my own. I'd like to make these ideas public, allow anyone to use them absolutely freely (even without mentioning me) and maintain these ideas on my blog/notes website.
Now let's say a reader leaves a comment and contributes with something extra, advancing the quest to solving the unsolved mathematical problem. Maybe he/she improved an idea I already posted. I want to then continue with my hobby free to use ideas that my readers are posting, meaning, make it clear that I don't owe them anything as I use their ideas, it is therefore their responsibility if they choose to post something under this condition. I don't want to get to be in a situation where someone demands something from me because 'they came up with it'. Once some mathematical result R is communicated from person A to person B, B cannot simply "undo" this exchange even if he wants to. He cannot simply pretend he "doesn't know" R.
How could I approach this? Is it enough to mention my conditions on my website? Would I be legally bound to anything in such a situation or is this actually a non-problem and I'm overthinking it?
(I'm not sure what the proper place to ask this is, I've also posted it on the 'law' stackexchange.)
 A: When it comes to legal rights, I think a disclaimer might suffice, though IANAL and you maybe should consult one.
When it comes to giving proper attribution and credit for ideas, I think this is not (or not only) something that an author owes to a specific originator of the ideas, but rather (or also) something an author owes to the community at large.  In particular, if I read your blog and make significant use of your original ideas to write a paper, and don't cite (or otherwise acknowledge) your blog, I have committed plagiarism whether you care or not.  Similarly, if I leave an important comment and you use it to write a paper, you are obliged to cite or acknowledge the comment whether I care or not.  (Note this obligation persists even if I remain completely anonymous, even untraceably so!)  This is because you have a duty to your readers to make as clear as possible the history of the ideas in your paper, in addition to anything you might "owe" me as originator of those ideas.
(There has been one situation where knowing that a particular theorem in a paper was due to an anonymous referee and not the author arguably led me to pursuing the right ideas in my own research.)
