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math.CO2025
Unavoidable butterfly minors in digraphs of large cycle rank
Meike Hatzel, O-joung Kwon, Myounghwan Lee +1
Cycle rank is one of the depth parameters for digraphs introduced by Eggan in 1963. We show that there exists a function such that every digraph of cyc…
math.CO2023
A characterization of graphs of radius- flip-width at most
Yeonsu Chang, Sejin Ko, O-joung Kwon +1
The -flip-width of a graph, for , is a graph parameter defined in terms of a variant of the cops and robber game, called the flipper game, and it…
math.CO2019
Graphs without two vertex-disjoint -cycles
Minjeong Kang, O-joung Kwon, Myounghwan Lee
Lovász (1965) characterized graphs without two vertex-disjoint cycles, which implies that such graphs have at most three vertices hitting all cycles. In this paper, we ask whether…