A linear kernel for planar total dominating set

A total dominating set of a graph G = (V,E) is a subset D ⊆ V such that every vertex in V is adjacent to some vertex in D. Finding a total dominating set of minimum size is NPcomplete on planar graphs and W [2]-complete on general graphs when parameterized by the solution size. By the meta-theorem of Bodlaender et al. [FOCS 2009], it follows that there exists a linear kernel for Total Dominating Set on graphs of bounded genus. Nevertheless, it is not clear how such a kernel can be effectively constructed, and how to obtain explicit reduction rules with reasonably small constants. Following the approach of Alber et al. [J. ACM 2004], we provide an explicit linear kernel for Total Dominating Set on planar graphs. This result complements several known constructive linear kernels on planar graphs for other domination problems such as Dominating Set, Edge Dominating Set, Efficient Dominating Set, or Connected Dominating Set.