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Several extremal problems on graphs involving the circumference, girth, and hyperbolicity constant

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 نشر من قبل Jose M. Rodriguez
 تاريخ النشر 2020
  مجال البحث
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To compute the hyperbolicity constant is an almost intractable problem, thus it is natural to try to bound it in terms of some parameters of the graph. Let $mathcal{G}(g,c,n)$ be the set of graphs $G$ with girth $g(G)=g$, circumference $c(G)=c$, and $n$ vertices; and let $mathcal{H}(g,c,m)$ be the set of graphs with girth $g$, circumference $c$, and $m$ edges. In this work, we study the four following extremal problems on graphs: $A(g,c,n)=min{delta(G),|; G in mathcal{G}(g,c,n) }$, $B(g,c,n)=max{delta(G),|; G in mathcal{G}(g,c,n) }$, $alpha(g,c,m)=min{delta(G),|; in mathcal{H}(g,c,m) }$ and $beta(g,c,m)=max{delta(G),|; G in mathcal{H}(g,c,m) }$. In particular, we obtain bounds for $A(g,c,n)$ and $alpha(g,c,m)$, and we compute the precise value of $B(g,c,n)$ and $beta(g,c,m)$ for all values of $g$, $c$, $n$ and $m$.



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