 The same notation can be used to describe other important families of sparse graphs, including trees, pseudoforests, and graphs of bounded arboricity.Based on this characterization, it is possible to recognize -vertex Laman graphs in time , by simulating a "pebble game" that begins with a graph with vertices and no edges, with two pebbles placed on each vertex, and performs a sequence of the following two kinds of steps to create all of the edges of the graph