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Nonseparating Cycles Avoiding Specific Vertices
Authors:Yanmei Hong  Liying Kang  Xingxing Yu
Institution:1. COLLEGE OF MATHEMATICS AND COMPUTER SCIENCE, FUZHOU UNIVERSITY, FUJIAN, CHINA;2. DEPARTMENT OF MATHEMATICS, SHANGHAI UNIVERSITY, SHANGHAI, CHINA;3. SCHOOL OF MATHEMATICS, GEORGIA INSTITUTE OF TECHNOLOGY, ATLANTA, GA
Abstract:Thomassen proved that every urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0001‐connected graph G contains an induced cycle C such that urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0002 is k‐connected, establishing a conjecture of Lovász. In general, one could ask the following question: For any positive integers urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0003, does there exist a smallest positive integer urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0004 such that for any urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0005‐connected graph G, any urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0006 with urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0007, and any urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0008, there is an induced cycle C in urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0009 such that urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0010 and urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0011 is l‐connected? The case when urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0012 is a well‐known conjecture of Lovász that is still open for urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0013. In this article, we prove urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0014 and urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0015. We also consider a weaker version: For any positive integers urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0016, is there a smallest positive integer urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0017 such that for every urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0018‐connected graph G and any urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0019 with urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0020, there is an induced cycle C in urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0021 such that urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0022 is l‐connected? The case when urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0023 was studied by Thomassen. We prove urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0024 and urn:x-wiley:03649024:media:jgt21845:jgt21845-math-0025.
Keywords:connectivity  nonseparating cycle  k‐contractible edge
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