Over time, there have been a number of posts on open problems remaining in different fields of math, both here and on the MathSE. So I had the idea of trying to construct a “list of lists” of problems from the many that exist — and it turns out someone else has already started such an effort!
I’ve found something quite neat, so I’ll be posting an answer below.
While looking for sets of open problems, I came across this site for The Association for Mathematical Research. I don’t know much about the organization, but apparently they have a page with sets of open problems by topic, currently over 100 lists, many of which seem active (like the Kourovka notebook for group theory).
So I’m going forward and sharing it here, for anyone who didn’t know. They also have an option to submit more open problems, making this a resource that hopefully lasts — maybe then fewer “what are open problems in field X” questions are needed in the future!
