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 Th82:
  for y,w holds w | y = ((y | y) | (y | y)) | w
proof
  let y,w;
  (y | y) | (y | y) = y by SHEFFER1:def 13;
  hence thesis by Th81;
end;
