Goal:
    G1 : t  ext : EdgeSet.t  x : VSet.elt
  ============================
   (transpose VSet.Equal fold_fun)


DEBUG:Going to execute:
move  =>[[xs ?] xt] [[ys ?] yt] ?
DEBUG LTAC Evaluated term: border_set
DEBUG LTAC Evaluated term: border_set
DEBUG LTAC Evaluated term: EdgeSet_fold_spec_right2
DEBUG LTAC Evaluated term: EdgeSet_fold_spec_right2