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 Th138:
  for q,w,y,x holds ((((x | (y | (y | y))) | w) | ((q | q) | w))
| ((w | (x | q)) | (w | (x | q)))) = (w | (((x | q) | (x | q)) | (w | (x | q)))
  )
proof
  now
    let y,p,w,q,x;
    ((w | (p | (p | p))) | (w | (x | q))) = w by Th134;
    hence ((((x | (y | (y | y))) | w) | ((q | q) | w)) | ((w | (x | q)) | (w |
    (x | q)))) = (w | (((x | q) | (x | q)) | (w | (x | q)))) by Th137;
  end;
  hence thesis;
end;
