Module VSM := VSM.Module CS  := Clausify_Sound VSM.Module SPS := SP_Sound VSM.Module NS  := Norm_Sound VSM.Module WFS := WF_Sound VSM.Module UFS := UF_Sound VSM.Module CL  := CL_Sound VSM.

Lemma positive_base_case : forall n: positive, O = nat_of_P n - 1 -> n=1%positive.