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 Th101:
  for w,y holds w | w = ((y | y) | y) | w
proof
  let w,y;
  w | ((y | y) | y) = w | w by Th70;
  hence thesis by Th83;
end;
