reserve L for satisfying_Sh_1 non empty ShefferStr;
reserve L for satisfying_Sheffer_1 satisfying_Sheffer_2 satisfying_Sheffer_3
  non empty ShefferStr;
reserve v,q,p,w,z,y,x for Element of L;

theorem Th97:
  for p,w holds p = (((w | w) | p) | (w | p))
proof
  let p,w;
  (w | w) | (w | w) = w by SHEFFER1:def 13;
  hence thesis by Th96;
end;
