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arXiv · 2312.17327

Characterization of cactus-expandable digraphs via doubly bidirectionally connected pairs

Hiroki Kodama
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Abstract

Azuma et al.\ showed that a strongly connected digraph without a doubly bidirectionally connected pair is cactus-expandable. We prove the converse: if a digraph has a doubly bidirectionally connected pair, then no expansion of it is a cactus digraph. Combined with the theorem of Azuma et al., this yields a characterization of strongly connected cactus-expandable digraphs.

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Hiroki Kodama. 2026-06-03. Characterization of cactus-expandable digraphs via doubly bidirectionally connected pairs. https://arxiv.org/abs/2312.17327

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