The 3-restricted edge-connectivity of the direct product graphs
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arXiv
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| Natura: | Preprint |
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2025
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| _version_ | 1866917110517596160 |
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| author | Wang, Wenxin Tian, Yingzhi |
| author_facet | Wang, Wenxin Tian, Yingzhi |
| contents | An edge subset \( S \subseteq E(G) \) is called a 3-restricted edge-cut if \( G - S \) is disconnected and each component of \( G - S \) contains at least three vertices. The 3-restricted edge-connectivity of a graph \( G \), denoted by \( λ_3(G) \), is defined as the minimum cardinality among all 3-restricted edge-cuts if there are at least one; otherwise, \( λ_3(G) = +\infty \). It is proved that $λ_3(G)\leqξ_3(G)$ if $G$ has a 3-restricted edge-cut, where $ξ_3(G) = \min \left\{ |[X, V(G) \setminus X]_G|:|X| = 3 \text{ and } G[X] \text{ is connected} \right\}.$ If \( λ_3(G) = ξ_3(G) \), then \( G \) is said to be maximally 3-restricted edge-connected. The direct product of two graphs $G$ and $H$, denoted by $G \times H$, is defined as the graph with vertex set \( V(G \times H) = V(G) \times V(H) \), where two vertices \( (u_1, v_1) \) and \( (u_2, v_2) \) are adjacent in \( G \times H \) if and only if \( u_1u_2 \in E(G) \) and \( v_1v_2 \in E(H) \). In this paper, we determine, for a regular connected graph \( G\), the 3-restricted edge-connectivity of \( G \times C_n \), \( G \times K_n \) and \( G \times T_n \), where \( C_n \), \( K_n \) and \( T_n \) are the cycle, the complete graph and the total graph with \( n \) vertices, respectively. As corollaries, we establish sufficient conditions for the direct product graphs \( G \times C_n \), \( G \times K_n \) and \( G \times T_n \) to be maximally 3-restricted edge-connected. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_22496 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The 3-restricted edge-connectivity of the direct product graphs Wang, Wenxin Tian, Yingzhi Combinatorics An edge subset \( S \subseteq E(G) \) is called a 3-restricted edge-cut if \( G - S \) is disconnected and each component of \( G - S \) contains at least three vertices. The 3-restricted edge-connectivity of a graph \( G \), denoted by \( λ_3(G) \), is defined as the minimum cardinality among all 3-restricted edge-cuts if there are at least one; otherwise, \( λ_3(G) = +\infty \). It is proved that $λ_3(G)\leqξ_3(G)$ if $G$ has a 3-restricted edge-cut, where $ξ_3(G) = \min \left\{ |[X, V(G) \setminus X]_G|:|X| = 3 \text{ and } G[X] \text{ is connected} \right\}.$ If \( λ_3(G) = ξ_3(G) \), then \( G \) is said to be maximally 3-restricted edge-connected. The direct product of two graphs $G$ and $H$, denoted by $G \times H$, is defined as the graph with vertex set \( V(G \times H) = V(G) \times V(H) \), where two vertices \( (u_1, v_1) \) and \( (u_2, v_2) \) are adjacent in \( G \times H \) if and only if \( u_1u_2 \in E(G) \) and \( v_1v_2 \in E(H) \). In this paper, we determine, for a regular connected graph \( G\), the 3-restricted edge-connectivity of \( G \times C_n \), \( G \times K_n \) and \( G \times T_n \), where \( C_n \), \( K_n \) and \( T_n \) are the cycle, the complete graph and the total graph with \( n \) vertices, respectively. As corollaries, we establish sufficient conditions for the direct product graphs \( G \times C_n \), \( G \times K_n \) and \( G \times T_n \) to be maximally 3-restricted edge-connected. |
| title | The 3-restricted edge-connectivity of the direct product graphs |
| topic | Combinatorics |
| url | https://arxiv.org/abs/2511.22496 |