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Four-Cycled Graphs with Topological Applications

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We call a simple graph G a 4-cycled graph if either it has no edges or every edge of it is contained in an induced 4-cycle of G. Our interest on 4-cycled graphs is motivated by the fact that their clique complexes play an important role in the simple-homotopy theory of simplicial complexes. We prove that the minimal simple models within the category of flag simplicial complexes are exactly the clique complexes of some 4-cycled graphs. We further provide structural properties of 4-cycled graphs and describe constructions yielding such graphs. We characterize 4-cycled cographs, and 4-cycled graphs arising from finite chessboards. We introduce a family of inductively constructed graphs, the external extensions, related to an arbitrary graph, and determine the homotopy type of the independence complexes of external extensions of some graphs.

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Correspondence to Türker Bıyıkoğlu.

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Both authors are supported by TÜBA through Young Scientist Award Program (TÜBA-GEBIİP/2009-06 and 2008-08).

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Bıyıkoğlu, T., Civan, Y. Four-Cycled Graphs with Topological Applications. Ann. Comb. 16, 37–56 (2012). https://doi.org/10.1007/s00026-011-0120-7

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  • DOI: https://doi.org/10.1007/s00026-011-0120-7

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