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Results tagged with open-problems
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user 4248
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?"
26
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Accepted
Is there a 7-regular graph on 50 vertices with girth 5? What about 57-regular on 3250 vertices?
This is the Moore graph, which is a regular graph of degree $d$ with diameter $k$, with maximum possible nodes. A calculation shows that the number of nodes $n$ is at most
$$
1+d \sum_{i=0}^{k-1} (d- …
- 1,250