A k-tree of a connected graph G is a spanning tree with maximum degree at most k. The rupture degree for a connected graph G is defined by , where and , respectively, denote the order of the largest component and numb...A k-tree of a connected graph G is a spanning tree with maximum degree at most k. The rupture degree for a connected graph G is defined by , where and , respectively, denote the order of the largest component and number of components in . In this paper, we show that for a connected graph G, if for any cut-set , then G has a k-tree.展开更多
Ecological environment in China refers to the state of people’s living environment,which is mainly represented in soil erosion,garbage pollution,air pollution,noise pollution and so on.The basic situation of ecologic...Ecological environment in China refers to the state of people’s living environment,which is mainly represented in soil erosion,garbage pollution,air pollution,noise pollution and so on.The basic situation of ecological environment in China is that the governance capacity is far behind the speed of destruction,and the ecological deficit is gradually expanding.Excessive deforestation,indiscriminate reclamation,exceeding hunting,and random wild plants picking have been failed to be prohibited.Forest fires and pests and diseases are still very serious threats to forestry.In this paper,based on the generality of sustainable development,a systematic discussion was made to the framework theory of sustainable forestry development and sustainable forest management,followed by further exploration of forest resources and sustainable development.Moreover,based on the investigation on related concepts of forest resources,review of historic process of forest resources,and analysis on the grim situation of forest resources,some countermeasures were proposed to carry out the sustainable utilization of forest resources in China.展开更多
The spectral radius of a graph is the maximum eigenvalues of its adjacency matrix. In this paper, using the property of quotient graph, the sharp upper bounds for the spectral radii of some adhesive graphs are determi...The spectral radius of a graph is the maximum eigenvalues of its adjacency matrix. In this paper, using the property of quotient graph, the sharp upper bounds for the spectral radii of some adhesive graphs are determined.展开更多
文摘A k-tree of a connected graph G is a spanning tree with maximum degree at most k. The rupture degree for a connected graph G is defined by , where and , respectively, denote the order of the largest component and number of components in . In this paper, we show that for a connected graph G, if for any cut-set , then G has a k-tree.
基金Project of Yangling Vocational and Technical College(BG2021002)。
文摘Ecological environment in China refers to the state of people’s living environment,which is mainly represented in soil erosion,garbage pollution,air pollution,noise pollution and so on.The basic situation of ecological environment in China is that the governance capacity is far behind the speed of destruction,and the ecological deficit is gradually expanding.Excessive deforestation,indiscriminate reclamation,exceeding hunting,and random wild plants picking have been failed to be prohibited.Forest fires and pests and diseases are still very serious threats to forestry.In this paper,based on the generality of sustainable development,a systematic discussion was made to the framework theory of sustainable forestry development and sustainable forest management,followed by further exploration of forest resources and sustainable development.Moreover,based on the investigation on related concepts of forest resources,review of historic process of forest resources,and analysis on the grim situation of forest resources,some countermeasures were proposed to carry out the sustainable utilization of forest resources in China.
文摘The spectral radius of a graph is the maximum eigenvalues of its adjacency matrix. In this paper, using the property of quotient graph, the sharp upper bounds for the spectral radii of some adhesive graphs are determined.
