5
votes
1answer
390 views

List of open problems of formal languages

As we know ,there are some open problems of formal languages,I am wandering if there is a somehow complete list of open problem of formal languages,or if there is no somehow complet one,May we make it ...
0
votes
0answers
231 views

Known and unknown about Ramanujan's tau function

What is a good reference for open problems relating to the Ramanujan tau function? I know about Lehmer's conjecture. I know the following reductions of the problem: the smallest counterexample must ...
11
votes
7answers
972 views

Open problems in the theory of compact quantum groups

What are the important open problems in the theory of compact quantum groups? Or conjectures? Here is an example from An De Rijdt's Ph.D. thesis: Is every compact quantum group with the fusion rules ...
4
votes
1answer
263 views

Open problems about CMC hypersurfaces with symmetries?

Recently, Andrews and Li announced a complete classification of CMC ($H=const.$) tori in $S^3$, confirming a conjecture of Pinkall and Sterling. Their main result is that any such torus is ...
34
votes
30answers
4k views

Fundamental problems whose solution seems completely out of reach [closed]

In many areas of mathematics there are fundamental problems that are embarrasingly natural or simple to state, but whose solution seem so out of reach that they are barely mentioned in the literature ...