Discrete Mathematics & Theoretical Computer Science, Vol 13, No 1 (2011)

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Cycle transversals in bounded degree graphs

Marina Groshaus, Pavol Hell, Sulamita Klein, Loana Tito Nogueira, Fabio Protti

Abstract


In this work we investigate the algorithmic complexity of computing a minimum Ck-transversal, i.e., a subset of vertices that intersects all the chordless cycles with k vertices of the input graph, for a fixed k ≥3. For graphs of maximum degree at most three, we prove that this problem is polynomial-time solvable when k ≤4, and NP-hard otherwise. For graphs of maximum degree at most four, we prove that this problem is NP-hard for any fixed k ≥3. We also discuss polynomial-time approximation algorithms for computing C3-transversals in graphs of maximum degree at most four, based on a new decomposition theorem for such graphs that leads to useful reduction rules.

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