Packing spanning partition-connected subgraphs with small degrees

Abstract

Let $G$ be a graph with $X\subseteq V(G)$ and let $l$ be an intersecting supermodular subadditive integer-valued function on subsets of $V(G)$. The graph $G$ is said to be $l$-partition-connected, if for every partition $P$ of $V(G)$, $e_G(P)\ge \sum_{A\in P} l(A)-l(V(G))$, where $e_G(P)$ denotes the number of edges of $G$ joining different parts of $P$. Let $\lambda \in [0,1]$ be a real number and let $\eta $ be a real function on $X$. In this paper, we show that if $G$ is $l$-partition-connected and for all $S\subseteq X$, $$\Theta_l(G \setminus S) \le \sum_{v\in S} (\eta(v) -2l(v))+l(V(G))+l(S)-\lambda (e_G(S))+l(S)),$$ then $G$ has an $l$-partition-connected spanning subgraph $H$ such that for each vertex $v\in X$, $d_H(v)\le \lceil \eta(v) -\lambda l(v) \rceil $, where $e_G(S)$ denotes the number of edges of $G$ with both ends in $S$ and $\Theta_l(G \setminus S)$ denotes the maximum number of all $\sum_{A\in P} l(A)-e_{G\setminus S}(P)$ taken over all partitions $P$ of $V(G)\setminus S$. Finally, we show that if $H$ is an $(l_1+\cdots +l_m)$-partition-connected graph, then it can be decomposed into $m$ edge-disjoint spanning subgraphs $H_1,\ldots, H_m$ such that every graph $H_i$ is $l_i$-partition-connected, where $l_1, l_2,\ldots, l_m$ are $m$ intersecting supermodular subadditive integer-valued functions on subsets of $V(H)$. These results generalize several known results.