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 Th143:
  for v,p,y,x holds p | (x | v) = (v | ((x | (y | (y | y))) | p)) | p
proof
  let v,p,y,x;
  (p | p) | ((x | (y | (y | y))) | p) = p by Th121;
  hence thesis by Th142;
end;
