The star-structure connectivity and star-substructure connectivity of hypercubes and folded hypercubes

As a generalization of vertex connectivity, for connected graphs $G$ and $T$, the $T$-structure connectivity $kappa(G, T)$ (resp. $T$-substructure connectivity $kappa^{s}(G, T)$) of $G$ is the minimum cardinality of a set of subgraphs $F$ of $G$ that each is isomorphic to $T$ (resp. to a connected subgraph of $T$) so that $G-F$ is disconnected. For $n$-dimensional hypercube $Q_{n}$, Lin et al. [6] showed $kappa(Q_{n},K_{1,1})=kappa^{s}(Q_{n},K_{1,1})=n-1$ and $kappa(Q_{n},K_{1,r})=kappa^{s}(Q_{n},K_{1,r})=lceilfrac{n}{2}rceil$ for $2leq rleq 3$ and $ngeq 3$. Sabir et al. [11] obtained that $kappa(Q_{n},K_{1,4})=kappa^{s}(Q_{n},K_{1,4})=lceilfrac{n}{2}rceil$ for $ngeq 6$, and for $n$-dimensional folded hypercube $FQ_{n}$, $kappa(FQ_{n},K_{1,1})=kappa^{s}(FQ_{n},K_{1,1})=n$, $kappa(FQ_{n},K_{1,r})=kappa^{s}(FQ_{n},K_{1,r})=lceilfrac{n+1}{2}rceil$ with $2leq rleq 3$ and $ngeq 7$. They proposed an open problem of determining $K_{1,r}$-structure connectivity of $Q_n$ and $FQ_n$ for general $r$. In this paper, we obtain that for each integer $rgeq 2$, $kappa(Q_{n};K_{1,r})=kappa^{s}(Q_{n};K_{1,r})=lceilfrac{n}{2}rceil$ and $kappa(FQ_{n};K_{1,r})=kappa^{s}(FQ_{n};K_{1,r})= lceilfrac{n+1}{2}rceil$ for all integers $n$ larger than $r$ in quare scale. For $4leq rleq 6$, we separately confirm the above result holds for $Q_n$ in the remaining cases.