Several results concerning contractible and removable edges in 3-connected finite graphs are extended to infinite graphs. First, we prove that every 3-connected locally finite infinite graph has infinitely many removable edges. Next, we prove that for any 3-connected graph , if is a finite degree vertex in and is not incident to any contractible edges, then is a finite cycle or contains a border pair. As a result, every 3-connected locally finite infinite graph contains infinitely many contractible edges. Lastly, it is shown that for any 3-connected locally finite infinite graph which is triangle-free or has minimum degree at least 4, the closure of the subgraph induced by all the contractible edges in the Freudenthal compactification of is topologically 2-connected.
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Xiamen Univ, Sch Math Sci, Xiamen 310065, Peoples R China
Guangxi Teachers Educ Univ, Sch Math Sci, Nanning 530001, Peoples R ChinaXiamen Univ, Sch Math Sci, Xiamen 310065, Peoples R China
Qin, Chengfu
Guo, Xiaofeng
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Xiamen Univ, Sch Math Sci, Xiamen 310065, Peoples R ChinaXiamen Univ, Sch Math Sci, Xiamen 310065, Peoples R China
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Xiamen Univ, Sch Math Sci, Xiamen 361005, Peoples R China
Jimei Univ, Sch Sci, Xiamen 361021, Peoples R ChinaXiamen Univ, Sch Math Sci, Xiamen 361005, Peoples R China
Xu, Liqiong
Guo, Xiaofeng
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Xiamen Univ, Sch Math Sci, Xiamen 361005, Peoples R ChinaXiamen Univ, Sch Math Sci, Xiamen 361005, Peoples R China