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2 votes
2 answers
273 views

Number of edge-disjoint cycles in a holey graph

Let $\Gamma$ be a connected graph with $H^1(\Gamma) \cong \mathbb{Z}^d$. Can we give a lower bound (preferably of the form $\gg d$) on the maximal number of edge-disjoint cycles one can find in $\...
H A Helfgott's user avatar
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2 votes
0 answers
137 views

How many edges can be in an unbalanced bipartite graph of girth $>6$?

Let $G = (V, E)$ be a bipartite graph with $n, m$ nodes in its bipartition and girth (shortest cycle length) $>6$. There is a simple counting argument called the Moore Bounds that gives $$|E| = O\...
GMB's user avatar
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1 vote
2 answers
205 views

Extremal density of a graph without a non-backtracking $2k$-cycle

The current best bound for the maximum possible density of an $n$-node graph with girth (shortest cycle length) $>2k$ is of the form $$ex(n \ \mid \ C_{\le 2k}) = O(n^{1 + 1/k}),$$ while the ...
GMB's user avatar
  • 1,389
7 votes
2 answers
8k views

How many simple cycles can a graph with $n$ vertices and $m$ edges have?

I am mainly interested in the smallest number of simple cycles a graph with $n$ vertices and $m$ edges must have. For example, if $m\le n-1$, this number is $0$, then if $n\le m \le 3(n-1)/2$, it is $...
domotorp's user avatar
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