论文标题
部分统治与独立部分统治之间的不平等
Inequalities between Partial Domination and Independent Partial Domination in Graphs
论文作者
论文摘要
对于图$ g $,一个顶点子集$ s \ subseteq v(g)$称为$ k_ {k {k} $ - 如果$ g -n_ {g -n_ {g} [s] $不包含$ k_ {k_ {k {k} $作为子级。 $ k_ {k} $ - $ g $的隔离数,由$ k {k}(g)$表示,是$ k_ {k {k} $的最小基数 - 隔离$ g $的隔离集。类似地,$ s $据说是独立的$ k_ {k} $ - 如果$ s $是$ k_ {k {k} $ - 隔离$ g $和$ g [s] $的隔离集没有边缘。独立的$ k_ {k} $ - $ g $的隔离数,由$ b'_ {k}(g)$表示,是独立$ k_ {k {k {k} $的最小基数 - $ g $的隔离集。显然,当$ k = 1 $时,我们有$γ(g)= 〜I_ {1}(g)$和$ i(g)=我'_ {1}(g)$,其中$γ(g)$和$ i(g)$是统治和独立的统治数字。 For classic results between $γ(G)$ and $i(G)$, in 1978, Allan and Laskar proved that $γ(G) = i(G)$ for all $K_{1, 3}$-free graphs and this result was generalized to $K_{1, r}$-free graphs by Bollob$\acute{a}$s and Cockayne in 1979. In 2013, Rad and Volkmann事实证明,当$δ(g)/2 $ $ i(g)/γ(g)$时,当$δ(g)/2 $当$δ(g)\ in \ {3、4、5 \} $时。此外,Furuya等。 al。证明当$δ(g)\ geq 6 $时,我们有$ i(g)/γ(g)\leqΔ(g)-2 \ sqrt {δ(g)} + 2 $。在本文中,对于最小的$ k_ {k} $ - 隔离套装$ s $,我们证明$ i'_k(g)\ le- \ frac {i_k^2(g)} {\ ell} +i_k(g)(δ +2) - \ ell use us $ n $ s $ s $ s $ s in Incomey y nound $ s in Incomey y nound $ s in Incomey nound $ s in In.是$ s $。我们证明了这一界限是锋利的。我们的主要定理的一个特殊情况暗示$ b'_ {k}(g)/| {k}(g)\leqΔ(g)-2 \ sqrt {Δ(g)} + 2 $。此外,当$ g $是$ g $是$ k_ {1,r} $ - 免费图形时,我们发现$〜$〜$〜'_ {k}(g)$之间的不平等。这也概括了Bollob $ \ acute {a} $ s和cockayne的结果。
For a graph $G$, a vertex subset $S \subseteq V(G)$ is said to be $K_{k}$-isolating if $G - N_{G}[S]$ does not contain $K_{k}$ as a subgraph. The $K_{k}$-isolation number of $G$, denoted by $ι_{k}(G)$, is the minimum cardinality of a $K_{k}$-isolating set of $G$. Analogously, $S$ is said to be independent $K_{k}$-isolating if $S$ is a $K_{k}$-isolating set of $G$ and $G[S]$ has no edge. The independent $K_{k}$-isolation number of $G$, denoted by $ι'_{k}(G)$, is the minimum cardinality of an independent $K_{k}$-isolating set of $G$. Clearly, when $k = 1$, we have $γ(G) = ι_{1}(G)$ and $i(G) = ι'_{1}(G)$ where $γ(G)$ and $i(G)$ are the domination and independent domination numbers. For classic results between $γ(G)$ and $i(G)$, in 1978, Allan and Laskar proved that $γ(G) = i(G)$ for all $K_{1, 3}$-free graphs and this result was generalized to $K_{1, r}$-free graphs by Bollob$\acute{a}$s and Cockayne in 1979. In 2013, Rad and Volkmann proved that the ratio $i(G)/γ(G)$ is at most $Δ(G)/2$ when $Δ(G) \in \{3, 4, 5\}$. Further, Furuya et. al. proved that when $Δ(G) \geq 6$, we have $i(G)/γ(G) \leq Δ(G) - 2\sqrt{Δ(G)} + 2$. In this paper, for a smallest $K_{k}$-isolating set $S$, we prove that $ι'_k(G)\le -\frac{ι_k^2(G)}{\ell} +i_k(G)(Δ+2)-\ell Δ$ where $\ell$ is the number of some specific vertices of $S$ such that the union of their closed neighborhoods in $S$ is $S$. We prove that this bound is sharp. A special case of our main theorem implies $ι'_{k}(G)/ι_{k}(G) \leq Δ(G) - 2\sqrt{Δ(G)} + 2$. Further, we find an inequality between $ι'_{k}(G)$ and $ι_{k}(G)$ when $G$ is $K_{1, r}$-free graph. This also generalizes the result of Bollob$\acute{a}$s and Cockayne.