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 Th134:
  for p,y,w holds (w | (y | (y | y))) | (w | p) = w
proof
  let p,y,w;
  (w | w) = (w | (y | (y | y))) by SHEFFER1:def 14;
  hence thesis by Th132;
end;
