Comments on ``The Einstein-Hilbert Lagrangian Density in a 2-dimensional   Spacetime is an Exact Differential'' by R. da Rocha and W.A. Rodrigues, Jr
  We argue that the recent result of da Rocha and Rodrigues that in two dimensional spacetime the Lagrangian of tetrad gravity is an exact differential [1], despite the claim of the authors, neither proves the Jackiw conjecture [2], nor contradicts to the conclusion of [3]. This demonstrates that the tetrad formulation is different from the metric formulation of the Einstein-Hilbert action. 
N. Kiriushcheva and S.V. Kuzmin