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Results tagged with open-problems
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user 4600
If it turns out that a problem is equivalent to a known open problem, then the open-problem tag is added. After that, the question essentially becomes, "What is known about this problem? What are some possible ways to approach this problem? What are some ways that people have tried to attack it before, and with what results?"
33
votes
Accepted
Is there a known Turing machine which halts if and only if the Collatz conjecture has a coun...
$\newcommand\PA{\mathit{PA}}$Let's note that this is not a question of whether Collatz is undecidable.
The statement $\neg\mathrm{Con}(\PA)$ is undecidable (by $\PA$, assuming $PA$ is consistent) but …
- 24.8k
13
votes
Accepted
Can any finite lattice be realized as an intermediate subgroups lattice?
This is an open problem. See
Wikipedia article: http://en.m.wikipedia.org/wiki/Finite_lattice_representation_problem
Palfy and Pudlak's result (see open-source description in Palfy's article Interva …
- 24.8k