Figure 4
From: On cycles in the transcription network of Saccharomyces cerevisiae
The smallest feedback vertex set of LSCC and the subdivision of LSCC. At least three feedback vertices are needed because there exists three vertex-disjoint cycles – indicated by wide color strips. If a single vertex selection on an indicated cycle suffices for the feedback vertex set then it must intersect every cycle that is vertex disjoint with the other indicated cycles; cycles indicated with thin color strips show that such selections are unique. A pictorial proof that {1, 3, 25} is the unique minimum feedback vertex set.