Improved Induced Matchings in Sparse Graphs

An induced matching in graph G is a matching which is an induced subgraph of G. Clearly, among two vertices with the same neighborhood (called twins) at most one is matched in any induced matching, and if one of them is matched then there is another matching of the same size that matches the other vertex. Motivated by this, Kanj, Pelsmajer, Schaefer and Xia [10] studied induced matchings in twinless graphs. They showed that any twinless planar graph contains an induced matching of size at least n 40 and that there are twinless planar graphs that do not contain an induced matching of size greater than n 27 + O(1). We improve both these bounds to n 28 +O(1), which is tight up to an additive constant. This implies that the problem of deciding an whether a planar graph has an induced matching of size k has a kernel of size at most 28k. We also show for the first time that this problem is FPT for graphs of bounded arboricity. Kanj et al. presented also an algorithm which decides in O(2159...

• Type: Conference
• Year: 2009
• Where: IWPEC
• Authors: Rok Erman, Lukasz Kowalik, Matjaz Krnc, Tomasz Walen
• Keywords: Applied Computing, IWPEC 2009, Planar Graph, Twinless Graphs, Twinless Planar Graphs