“…Embeddings of graphs with a regular structure, like rings, (multidimensional) grids, complete trees, binomial trees, pyramids, X-trees, meshes of trees etc., have been extensively investigated, see, e.g., [1,2,3,4,5,6,7,8,9,10,11,12,13]. However, these regular structures become less applicable if, as happens in many cases, the communication structure of a parallel algorithm is very irregular.…”