Richard Hamming in his 1986's very nice essay titled ``You and Your Research'' (full text with comments is available via https://www.cs.virginia.edu/~robins/YouAndYourResearch.html) says that it is very important to ask yourself and your colleagues the following three questions (he actually did this):
1. What are the important problems of your field?
2. What important problems are you working on?
3. If what you are doing is not important, and if you don't think it is going to lead to something important, why are you [...] working on it?
During the OPSO 2021 online conference we are collecting open problems in one-parameter operator (semi)group theory. You are welcome to contribute problems, to comment contributed problems, to add relevant references. Maybe some problems are already solved but only few people know about this fact. Maybe some important open problems are not well known to the whole community. We have the OPSO 2021 conference to clarify the state of the art in this field. You are welcome to discuss all this during each day of the conference.
We use Overleaf online TeX editor to collect problems and comments. Also we will publish on the present webpage the PDF version of the text, but please keep in mind that the Overleaf version has higher priority. After we obtain the stable version of the text we will publish it in one of the mathematical journals (if you think that you should be a coauthor of this paper please let us know).
Overleaf read-only link (to open it you need to be registered on the Overleaf, the registration is fast and free): https://www.overleaf.com/read/yfwxhwfzctcn
If you wish to contribute to this text by submitting problems, comments, references or corrections then please write a letter to Ivan Remizov via firstname.lastname@example.org and you will be provided with a link which allows editing.