Rambow and Satta (1999) categorize the generative capacity of LCFRS grammars according to their rank and fan-out.
they show that grammars can be arranged in a two-dimensional grid, with languages of rank r and fan-out f having greater generative capacity than both grammars of rank r and fan-out f − 1 and grammars of rank r − 1 nmod sbj root vc pp nmod np tmp A hearing is scheduled on the issue today Figure 4: A dependency tree with the LCFRS rules extracted for each word (Kuhlmann and Satta, 2009).